@node Game Design

@chapter Designing Games with Xconq

This chapter is an introduction to the process of designing games
for @i{Xconq}.  First we will build a simple but complete game,
then we will go through the major parts of a design and see how it
all works.  Sections on specific techniques and the use of online
design tools follow.

Note that this chapter does not formally define any of the GDL
constructs mentioned.  You may find the complete formal definitions
in the reference manual in the next chapter.

@menu
* A Tutorial Example::            
* Types::                       
* Setting up a Game::           
* Designing the World::         
* Designing the Sides::         
* Setting up the Units::         
* Setup Miscellany::            
* Units and Actions::            
* Unit Movement::            
* Unit Construction::            
* Unit Combat::            
* Unit Manipulation::            
* Material Manipulation::       
* Terrain Manipulation::        
* Vision Parameters::            
* Designing Backdrop Weather::            
* Designing Backdrop Economy::            
* Adding Random Events::            
* Designing the Interface::            
* Designing the Text::              
* Designing the Graphics::            
* Game Module Organization::            
* Building New Games::            
* Debugging Designs::                   
* Tricks and Techniques::            
* Designing with the Common Interface::
* Designing with the Mac Interface::
@end menu

@node A Tutorial Example
@section A Tutorial Example

Before delving into the depths of the language, let's look at an
example.  Suppose you just finished watching a Godzilla movie, complete
with roaring monsters, panic-stricken mobs, fire trucks putting out
flames, and so forth, and were inspired to design a game around this
theme.

@menu
* Basic Definitions::           
* Adding Movement::             
* Buildings and Rubble Piles::  
* Human Units::                 
* The Scenario::                
@end menu

@node Basic Definitions
@subsection Basic Definitions

Start by opening up a file, calling it something like @code{g-vs-t.g},
or some other name appropriate for your type of machine, and then type
this into it:
@example
(game-module "g-vs-t"
  (title "Godzilla vs Tokyo")
  (blurb "Godzilla stomps on Tokyo")
)
@end example

This is a GDL @dfn{form}.  It declares the name of the game to be
@code{"g-vs-t"}, gives it a title that prospective players will see in
menus, plus a short description or @dfn{blurb}.  The blurb should tell
prospective players what the game is all about, perhaps whether it is
simple or complex, or whether it is one-player or multi-player.  Both
title and blurb are examples of @dfn{properties}, which are like slots
in structures.

The @code{game-module} form is optional but recommended; some interfaces
use it to add the game to a list of games that players can choose from.

The general syntax of @code{game-module} form is similar to that used by
nearly all GDL forms; it amounts to a definition of an ``object'' (such
as a game module or a unit type) with @dfn{properties} (such as name,
description, speed, etc).  Some properties are required, and appear at
fixed positions, while others are optional and can be specified in any
order, so they are introduced by name.  The general format, then, looks
like
@example
(<object> ... <required properties> ...
  ...
  (<property name> <property value>)
  ...
  )
@end example
There are very few exceptions to this general syntax rule.

(People often have trouble with parentheses in Lisp, but if you follow
the same kinds of indentation rules that you always use in C or Pascal,
then you will encounter no additional trouble.  Also, many editors such
as Emacs are intelligent enough to indicate when parentheses match, and
automatically do proper indentation.)

Now the first thing you'll need is a monster.  In @i{Xconq}, each unit
has a type, and you define the characteristics attached to the type.
@example
(unit-type monster)
@end example
This declares a new unit type named @code{monster}, but says nothing
else about it.  Let's use this more interesting form instead:
@example
(unit-type monster
  (image-name "monster")
  (help "crushes, crumbles, and chomps")
  (start-with 1)
)
@end example
This shows the usual way of describing the monster.  In this case,
@code{image-name} is a property that specifies the name of the icon that
will be used to display a monster.  (@i{Xconq} comes with a library of
over 700 icons, of which "monster"; it looks a little like Godzilla.)
The property @code{start-with} says that each side should start out with
one monster.  This isn't quite right, because there should only be one
side with a monster, and this will give @i{each} side a monster to start
out with, but we'll see how to fix that later on.

We also need at least one type of terrain for the world:
@example
(terrain-type street (image-name "gray"))
@end example

These two forms are actually sufficient by themselves to start up a
game.  (Go ahead and try it.)  However, you'll notice that the game is
not very interesting.  Although each player gets a monster, and the
world consists of all-street terrain, nobody can actually @emph{do}
anything, and turns just whiz by, since the defaults basically turn off
all possible actions.

@node Adding Movement
@subsection Adding Movement

OK, let's give the monsters the ability to act by putting this form into
the file:
@example
(add monster acp-per-turn 4)
@end example

The @code{add} form is very useful; it says to @i{modify} the existing
type named @code{monster}, setting the property @code{acp-per-turn} to
4, overwriting whatever value might have been there previously.  The
@code{acp-per-turn} property gives the monster the ability to act, up to
4 actions in each turn.  By default, the ability to act is 1-1 with the
speed of the unit, so the monster can also move into a new cell 4 times
each turn.  If you run the game now, you will find that your monster can
now get around just fine.

Why 4?  Actually, at this point the exact value doesn't matter, since
nothing else is happening.  If the speed is 1, then the turns go faster;
if the speed is 10, then they go slower and more action happens in a
single turn.  In a complete design however, the exact speed of each unit
can be a critical design parameter, and for this game, I figured that a
speed of 4 allowed a monster to cover several cells in a hurry while not
being able to get too far.  Also, I'm planning to make panic-stricken
mobs have a speed of 1, which is the slowest possible.  Making actions
1-1 with speed is usually the right thing to do, since then a player
will get to move 4 times each turn (later on we will see reasons for
other combinations of values).

The @code{add} form works on most types of objects.  It has the general
syntax
@example
(add <type(s)/object(s)> <property name> <value(s)>)
@end example
The type or object may be a list, in which the value is either given to
all members of the list, or if it is a list itself, then the list of
values is matched up with the list of types.

@node Buildings and Rubble Piles
@subsection Buildings and Rubble Piles

To give the monster something to do besides walk around, add buildings
as a new unit type:
@example
(unit-type building (image-name "city20"))

(table independent-density (building street 500))
@end example
The @code{building} type uses an icon that is normally used for a
20th-century city, but it has the right look.  The
@code{independent-density} table says how many buildings will be
scattered across in the world.  The @code{table} form consists of the
name of the table followed by one or several three-part lists; the two
indexes into the table, and a value.  In this case, one index is a unit
type @code{building}, the other is a terrain type @code{street}, and the
value is @code{500}, which means that we will get about 500 buildings
placed on a 100x100 world (look up the definition of this table in the
index).  You need some for testing purposes, otherwise you won't see any
when you start up the game.

@c In general,
@c @i{Xconq} policy is not to do anything unless you've turned it on first,
@c and then to give you ``reasonable'' defaults once things are turned on.

We're going to let buildings default to not being able to do anything,
since that seems like a reasonable behavior for buildings (although Baba
Yaga's hut might be fun...).

By default, buildings act strictly as obstacles; monsters cannot touch
them, push them out of the way, or walk over them.  In real(?) life of
course, monsters hit buildings, so we have to define a sort of combat.
@example
(table hit-chance
  (monster building 90)
  (building monster 10)
  )

(table damage
  (monster building 1)
  (building monster 3)
  )

(add (monster building) hp-max (100 3))
@end example
The @code{hit-chance} and @code{damage} tables are the two basic tables
defining combat.  The hit chance is simply the percent chance that an
attack will succeed, while the damage is the number of hit points that
will be lost in a successful attack.  The unit property @code{hp-max} is
the maximum number of hit points that a unit can have, and by default,
that is also what units normally start with.

Note that the @code{add} form allows lists in addition to single types
and values, in which case it just matches up the two lists.  The
@code{add} tries to be smart about this sort of thing; see its official
definition for all the possibilities.

The net effect of these three forms is to say that a monster has a 90%
chance of hitting a building and causing 1 hp of damage; three such hits
destroy the building.  A monster's knuckle might occasionally be skinned
doing this; a 10% chance of 3/100 hp damage is not usually dangerous,
and feels a little more realistic without complicating things for the
player.

Now you can start up a game, and have your monster go over and bash on
buildings.  Simulated wanton destruction!

By default, a destroyed building vanishes, leaving only empty terrain
behind.  If you want to leave an obstacle, define a new unit type and
let the destroyed building turn into it:
@example
(unit-type rubble-pile)

(add building wrecked-type rubble-pile)
@end example
(Incidentally, you need to add the unit-type before any tables are
defined, so that Xconq knows how big the tables need to be.)

In practice, you have to be careful to define the behavior of rubble
piles.  What happens when a monster hits a rubble pile?  Can the rubble
pile be cleared away?  Does it affect movement?  Try these things in a
game now and see what happens; sometimes the behavior will be sensible,
and sometimes not.

For instance, you will observe that the default behavior is for the
rubble pile to be an impenetrable obstacle!  The monster can't hit it,
and can't stand on it, and in fact can't do anything at all.  OK, let's
fix it.  Monsters are agile enough to climb over all sorts of things, so
the right thing is to let the monster co-occupy the cell that the rubble
pile is in.  The default is to only allow one unit in a cell, but this
can be changed:
@example
(table unit-size-in-terrain (rubble-pile t* 0))
@end example
This says that while all other units have a size of 1, rubble piles only
have a size of 0.  By default, each terrain type has a capacity of 1, so
this allows one unit and any number of rubble piles to stack together in
a cell.

If you try this out, you'll find that the monster can now cross over
rubble piles, but still has to bash buildings in order to get them out
of the way. (Well, actually you probably need to play with zones of
control as expressed in terms of mp-to-enter-zoc and others to get
this example to work as-is.  Or put the monster and the rubble-pile on
same side, or some such).
@c Anyone want to try the tutorial on a modern xconq and see what else
@c is broken?

Incidentally, it can cause problems to set a unit size to zero, because
it allows infinite stacking.  Since buildings and rubble piles don't
move, there will never be more than one in a cell, but @i{Xconq} will
happily let hundreds of units share the same cell, which works, but
causes no end of headaches for players confronted with overloaded
displays.

@c A game is more playable if it has at least some limits
@c on stacking.  For instance, this limits stacking of rubble piles,
@c and also keeps the monster out of really full-up places:
@c @example
@c (table unit-size-in-terrain (u* t* 1))
@c 
@c (add t* unit-capacity 16)
@c @end example

@node Human Units
@subsection Human Units

Now you've got an ``interactive experience'' but no game; there's no
challenge or goal.  You could maybe make a two-or-more-player game where
the players race to see who can flatten the mostest the fastest, but
that's still not too interesting to anyone past the age of 5.  Instead,
we need to make some units for the people bravely (or not so bravely)
resisting the monster's depredations:
@example
(unit-type mob (name "panic-stricken mob") (image-name "mob"))
(unit-type |fire truck| (image-name "firetruck"))
(unit-type |national guard| (image-name "soldiers"))
@end example
Note that a type's name may have an embedded space, but then you have to
put vertical bars around the whole symbol.  Things are starting to get
complicated, so let's define some shorter synonyms:
@example
(define f |fire truck|)
(define g |national guard|)

(define humans (mob f g))
@end example
You can use the newly defined symbols @code{f} and @code{g} anywhere in
place of the original type names.  The symbol @code{humans} is a list of
types, and will be useful in filling several propertys at once.

As with monsters, all these new units should be able to move:
@example
(add humans acp-per-turn (1 6 2))
@end example
The speeds here are adjusted so that monsters can chase and run down
(and presumably trample to smithereens) mobs and guards, but fire trucks
will be able to race away.

Also note the use of a three-element list that matches up with the three
elements in the @code{humans} list.  This is a very useful features of
GDL, and used heavily.  It can also be a problem, since if you add or
remove elements from the list @code{humans}, every list that it is
supposed to match up with also has to change.  Fortunately, @i{Xconq}
will tell you if any lists do not match up because they are of different
lengths.

We still need to define some interaction, since monsters and humans can
make faces at each other, and get in each other's way, but otherwise
cannot interact.
@example
(table hit-chance add
  (monster humans 50)
  (humans monster (0 10 70))
  )
@end example
This time we have to say ``add table'' because we've already defined the
@code{hit-chance} table and now just want to augment it.  (Be sure to
place this form after the first @code{hit-chance} table definition.)

As with the addition of properties, we can use a list in place of a
single type.

Last but not least, we need a scorekeeper to say how winning and losing
will happen.  This is a simple(-minded?) game, so a standard type will
be sufficient:
@example
(scorekeeper (do last-side-wins))
@end example
The @code{do} property of a scorekeeper may include some rather
elaborate tests, but all we want to is to say that the last side left
standing should be the winner, and the symbol @code{last-side-wins} does
just that.

There might be a bit of a problem with this in practice, since in order
to win, the monster has to stomp on all the humans, including fire
trucks.  But fire trucks can always outrun the monster, and cannot
attack it directly either, which leads to a stalemate.  You can fix this
by zeroing the point value of fire trucks:
@example
(add f point-value 0)
@end example
Now, when all the mobs and guards have been stomped, the monster wins
automatically, no matter how many fire trucks are left.

@node The Scenario
@subsection The Scenario

As it now stands, your game design requires @i{Xconq} to generate all
kinds of stuff randomly, such as the initial set of units, terrain, and
so forth.  However, we @emph{are} doing a monster movie, so random
combinations of monsters and people and terrain don't usually make
sense.  Instead of trying to define a ``reasonable'' random setup, we
should define a scenario, either by starting a random game, modifying,
and saving it, or by text editing.  Since online scenario creation is
hard to describe in the manual, let's do it with GDL instead.

To define a scenario, we generally need three things: sides, units, and
terrain.  Now the basic monster movie idea puts one monster up against a
bunch of people acting together, so that suggests two sides:

@example
(side 1)

(side 2 (name "Tokyo") (adjective "Japanese"))
@end example

The @code{1} and @code{2} identify the two sides uniquely, since we'll
have to match units up with them in a moment.  The side that plays the
monster is really a convenience; players should just be aware of the one
monster unit, so we don't need any sort of names.  The other side has
many units, which should be qualified as @code{"Japanese"}, and the side
as a whole really represents the city of Tokyo, so use that for the
side's name.

Now for the units:

@example
(unit monster (s 1) (n "Godzilla"))

(unit f (s 2))
(unit f (s 2))

(building 9 10 2)

(define b building)  ; abbreviate for compactness' sake

(b 10 10 2)
(b 11 10 2 (n "K-Mart"))
(b 12 12 2 (n "Tokyo Hilton"))
(b 13 12 2 (n "Hideyoshi's Rice Farm"))
(b 14 12 2 (n "Apple Japan"))
;; ... need lots of buildings ...
@end example

This example shows two syntaxes for defining units: the first is
introduced by the symbol @code{unit} and requires only a unit type (or
an id, see the definition in xxx), while the second is introduced by the
unit type name itself and requires a position and side.  The second form
is more compact and thus suitable for setting up large numbers of units,
while the first form is more flexible, and can be used to modify an
already-created unit.  In both cases, the required data may be followed
by optional properties in the usual way.

Also, since the word ``building'' is a little longwinded, I defined the
symbol ``b'' to evaluate to ``building''.  GDL has very few predefined
variables, so you can use almost anything, including weird stuff like
``&'' and ``=''.  Property names like @code{s} and @code{n} are NOT
predefined variables, so you can use those too if you like.

At this point, you should have a basic game scenario, with one player
being Godzilla, and the other trying to keep it from running amuck and
flattening all of Tokyo.  Have fun!

You can enhance this scenario in all kinds of ways, depending on how
ambitious you want to get.  Given the basic silliness of the premise,
though, it would be more worthwhile to enhance the silliness and speed
up the pace, rather than to add features and details.  For instance,
name the buildings after all the laughingstock places you know of in
your own town.

To see where you could go with this, look at the library's
@code{monster} game and its @code{tokyo} scenario, which include fires,
different kinds of terrain, and other goodies.

@node Types
@section Types

Types are the foundation of all @i{Xconq} game designs.  Types are like
classes in object-oriented programming but simpler; each set of types is
fixed and used only in a particular way by @i{Xconq}.  A game design
defines types of units, materials, and terrain.  Only materials are
optional; every game design must define at least one unit type and one
terrain type.

Types in GDL are simple compared to most other languages.  There is no
inheritance, no subtyping, no coercions or conversions.  This is not a
real limitation, since game designs are usually too small to make
effective use of any sort of inheritance.  Also, game design is an
exacting activity; inheritance is often difficult to control
satisfactorily.  You can use lists of types to simulate inheritance as
necessary; this is actually more flexible, because you can have any
number of lists with any set of types in each.  It may not seem as
efficient, but GDL is only used during startup, and is almost entirely
array- and struct-based during the game.  (A few places, such as
scorekeeping, examine GDL forms during play.)

Types are defined one at a time in the game module file.  Each type gets
an index from 0 on up, in order of the type's appearance in the file.
Although this is not normally visible to you or to the player, some
error messages and other places will make reference to raw type indices.
Each category of type - unit, material, and terrain is indexed
individually.
 
@menu
* Designing Unit Types::                  
* Designing Terrain Types::               
* Designing Material Types::              
* Setting up Type Relationships::          
* Stacking::                    
* Defining Occupants and Transports::    
* Hints on Types::              
@end menu

@node Designing Unit Types
@subsection Designing Unit Types

Unit types define what the players get to play with.  Unit types can
include almost anything; people, buildings, airplanes, monsters, arrows,
boulders, you name it.

The basic form of a unit type definition is so:
@example
(unit-type @var{type-name} (@var{property-name} @var{property-value}) @dots{})
@end example
The appearance of this form in a file means you are adding a new and
distinct type, which has no relation to any other types defined before
and after this one.  The @var{type-name} must be a unique symbol, such
as @code{building} or @code{|fire truck|}. (Note that you can set things
up so that players never see the @var{type-name} anywhere, so don't
worry if your preferred name conflicts with something else, just choose
another name.)  The @var{property-name} and @var{property-value} pairs
are entirely optional.  They can always be defined or changed later in
the file.  There is little advantage one way or another.

This particular syntax - keyword followed by name or other identifier
followed by property/value pairs - will be used for most GDL definitions.

The number of unit types is limited.  The exact limit depends on the
implementation, but is guaranteed to be at least 127.  This is a huge
number of types in practice; the only situations where this might be
needed would be a fantasy-type game with many types of items and
monsters.  For empire-building games, 8-16 unit types is far more
reasonable.  Keep in mind that with lots of types, players have more to
keep track of, internal data structures will be larger and take longer
to work with, and designing the game will take more time and energy.
Consider also that @i{Xconq} gives you a lot of properties that you can
set individually for each unit type, so that when other game systems
might require a distinct types, @i{Xconq} lets you use the same type
with different propertys.  For instance, in a fantasy game you wouldn't
need to define ``young dragons'' and ``old dragons'' as distinct types,
instead you can vary the hit points or experience of a generic
``dragon'' type.

@node Designing Terrain Types
@subsection Designing Terrain Types

Each cell in the world has a terrain type.  This type should be thought
of as the predominant contents of the cell, whether it be open ground,
forest, city streets, or the vacuum of deep space.  The type can be
anything you want, and should be adapted to fit the game you're
designing.  Sure, the real world has swamps, but if you're designing a
game set in the Sahara, don't bother defining a swamp terrain type.
Also, the type doesn't carry any preconceptions about elevation or
climate, so you can have swamps at 20,000 feet just as easily as at sea
level.

The limit on the number of terrain types is large (up to about 127,
depending on the implementation), but in practice, 6-10 types offer
variety without being confusing.  Ideally, several of those types will
be uncommon in the world, so that map displays will consist mostly of
3-4 types of terrain.

Some game designs involve entities that are very large and do not move
around.  Such entities could plausibly be represented either as
non-moving units or as a distinct terrain type.  To make the right
choice, you need to consider the special characteristics you want to
implement.  Terrain cannot (usually) be changed during the game, nor can
it be moved, but units can be damaged or belong to different sides.  A
realistic example of this choice occurs in the monster game - should a
destroyed building become a ``rubble-pile'' unit or should the building
stand on rubble-pile terrain and vanish when it is destroyed?  Both
choices are plausible; if the rubble-pile is a unit, then the original
building is then on top of an empty city block, and after the building
is destroyed, the rubble-pile unit can itself be cleaned off, exposing
the empty city block again.  However, you have to decide whether the
rubble-pile unit belongs to a side, how it interacts with other units,
and so forth.  Rubble-pile terrain is simpler, but the players then get
descriptions of brand-new buildings sitting in the midst of
rubble-piles, which is confusing.  This is a case where there is no
``right'' answer.

@node Designing Material Types
@subsection Designing Material Types

Material types are the simplest to define.  They have only a few properties
of their own; most of the time they just index tables along with the
other types.
Materials do not act on their own in any way; instead, players
manipulate materials as part of doing other actions.
For instance, you can specify that movement, combat, and even a
unit's very survival depends on having a supply of some material,
or that some material is ammo and consumed gradually when fighting.

The use of materials is pretty much up to you.  You don't have to
define any material types at all,
and game designs with materials are usually more complicated.
However, the increase in realism is often worth it;
with materials you can limit player activity
and/or make some actions more ``expensive'' than others.

As with the other types, you can define up to about 127 material types,
but that would be enough to model the entire global economy
accurately! (and take all week to compute a single turn...)
1-3 types is reasonable.

@node Setting up Type Relationships
@subsection Setting up Type Relationships

The next sections describe the ``static'' relationships between types of
objects, meaning those relations which must always hold, both in the
initial setup and throughout a game.

@node Stacking
@subsection Stacking

By default, @i{Xconq} allows only one unit in each cell at a time.
This has the advantage of simplicity, but also makes some bizarre
situations, such as the ability of a merchant ship to prevent an
airplane from passing overhead or a submarine from passing underneath.

To fix this, you can allow players to stack several units in the
same cell.  This is governed by several tables, which give you control
over which and how many of each type can stack together in which kinds
of terrain.  The basic idea is that a cell has a certain amount of room
for units, as specified by the terrain type property @code{capacity},
and each unit has a certain size in the cell, according to the table
@code{unit-size-in-terrain}.

@example
(add (plains canyons) capacity (10 2))

(table unit-size-in-terrain
  ((indians town) plains (1 5))
  ((indians town) canyons (1 2))
  )
@end example

In this example, a player can fit 10 indians or 2 towns into a plains cell,
or else one town and 5 indians, while canyons allow only 2 indians or one town.

In addition, some unit types may be able to count on a terrain type providing
a guaranteed place; for this, you can use the unit/terrain table
@code{terrain-capacity-x}.  This table (which defaults to 0) allows
the specified number of units of each type to be in each type of
terrain, irrespective of who else is there.  For instance,
a space station could be given space via
@example
(table terrain-capacity-x (space-station t* 10000))
@end example
So while units on the ground are piling together and being constrained
by capacity, space stations overhead can stack together freely (space
is pretty big, after all).

@node Defining Occupants and Transports
@subsection Defining Occupants and Transports

Occupants and transports work similarly to stacking in terrain;
there is both a specialized capacity and a generic capacity that
units' sizes count against.

@example
(add (transport carrier) capacity (8 4))

(table unit-size-as-occupant
  ((infantry armor) transport (1 2))
  ((fighter bomber) carrier (1 4))
  )

(table unit-capacity-x
  (carrier fighter 4)
  )
@end example

It may be that all the different sizes interact so that you can't
prevent huge numbers of small units being able to occupy a single
transport.  To fix this, use @code{occupants-max}.

Transport is a physical relationship, so for instance one cannot use
transports to define a convoy whose acp-per-turn is determined by its
slowest member.  (This doesn't mean you can't define a convoy
type, but you will have to pick an arbitrary speed for it.)

Watch out for unexpected side effects of setting the @code{capacity}
but not the @code{unit-size-as-occupant}!  Since @code{unit-size-as-occupant}
defaults to 1, then a unit with a nonzero capacity can by default
take on @i{any} other type as an occupant!

Also, don't let units carry others of their own type.
Not only is this of doubtful meaning,
@i{Xconq} is not guaranteed to cope well with this situation,
since it allows infinite recursion in the occupant-transport relation.
Ditto for loops; ``A can carry B which can carry C which can carry A''.

@node Hints on Types
@subsection Hints on Types

It is tempting to try to define independent sets of types,
each in a separate module, and glue them together somehow.
However, this doesn't work well in practice, because in a game,
the types interact in unexpected ways.
Suppose, for example, that you define a set of airplane types that
you want to be generic enough to use with several different games.
The assessment of those types may vary drastically from game to game;
in one, airplanes are 100 times faster than any other sort of unit,
so that moving airplanes takes up 99% of game play, while in another,
the same set of airplane types are too weak to be of any interest to
players.

There is a standard set of terrain types called @code{"stdterr"}.
This set has a mix of the types found most useful for ``Empire-type'' games,
and Earth-like percentages for random world generation.

@node Setting up a Game
@section Setting up a Game

You have a spectrum of options for how @i{Xconq} will set up a game
based on your design.  At the one end, you can build a scenario that
specifies everything exactly, down to the last unit.  Lest you think
this is too restrictive to be interesting, consider that this is
how chess works...
At the other end of the spectrum,
you can let @i{Xconq} manufacture everything,
starting only with a handful of numbers that you supply.

The next several sections describe the alternatives available for
game setup.  It is important to understand what is possible,
because in general the character of an @i{Xconq} game will depend
strongly on the initial setup, and players will be very angry
(with you!) if they discover, several hours into a hard-fought game,
that they've been given a grossly unfair starting position.

@node Designing the World
@section Designing the World

The @i{Xconq} world/area is a two-dimensional grid of fixed shape and
size.  You can treat it as representing part of a planet in space, and
set up parameters simulating that, or just make it be itself and not
address the question of the surrounding context.  The appropriate choice
depends on how much realism and complexity you need.  Most computer
games don't bother with this detail; for instance, a game set in an
underground dungeon doesn't usually need to compute daylight, weather,
or seasons.  However, these same details may be very useful for games
set outdoors.

@menu
* World Shape and Size::        
* World Terrain::               
* Synthesizing World Terrain::  
* Rivers::                      
* Roads::                       
* Independent Units::           
* Altitudes and Elevations::
* World Setup Miscellany::
@end menu

@node World Shape and Size
@subsection World Shape and Size

Once you've decided whether the area is to be part of a planet or not,
you can address the question of size and shape.
You have two choices for shape: hexagon and cylinder.
(See the players chapter for pictures of these.)
The important thing for you as a designer is that the cylinder
wraps around, while the hexagon is bounded on all sides.
One consequence is that games involving pursuit will be quite
different; on a cylinder, the chase can go 'round and 'round forever,
while on a hexagon, a fleeing unit could be cornered.
Cylinders have a disadvantage in that there is no obvious ``starting place''
for coordinates, scrolling, etc, so there is a navigation and orientation
problem for players, especially if the world is randomly generated and not
the familiar continents of the Earth.  In fact, players will often not
even realize that a world is a cylinder and will assume that the edge
of the display is the edge of the world!  To make a cylindrical area,
set the circumference of the world equal
to the width of the area.  Otherwise, the area will be handled as a hexagon.

You can choose either to set a fixed size using the @code{area} form,
or allow players to set the actual size via the @code{world-size} variant,
in which case you can define the allowable range of sizes.

Worlds need not be really large.  Larger worlds are harder for
players to manage, they take longer to display, and can consume
prodigious amounts of memory (since they are represented as arrays
internally, for speed).  The ideal range of sizes depends primarily
on the size and speed of units.  A 60x60 area in a game with units whose
speed is 1 means that they will take 60 turns to cross, while units with
a speed of 20 take only 3 turns, so they make the world ``feel smaller''.
As another example, in the standard game,
a 20x20 area allows player to come to grips quickly, but it also
means that each player's units might be within attack range right
from the outset, which has a drastic effect on strategy.
For exploration-oriented games, larger worlds are more interesting.

@node World Terrain
@subsection World Terrain

The best technique for designing the terrain of a world is to use the
designer tools provided with @i{Xconq}.  The details of how these tools
work depends on the interface, but in general they resemble the tools
found in paint programs.  Some interfaces also give you the option of
rescaling the map, so that you can fine-tune the size and positioning of
the terrain.

Another technique is to write a program that translates data from
another source (such as NASA satellite data) into @i{Xconq} format.
However, if you take a rectangular array of data and just wrap an
@code{area (terrain ...))} form around it, then everything will appear
to be tilting to the left.  To fix this, have your program map the cell
at @code{x, y} in the rectangular array to @code{x - y / 2, y} before
writing.  You must discard values whose new @code{x} coordinate is
negative, or else wrap them around to the right side of the area,
although that is usually only reasonable for cylindrical areas.

The crudest technique is to try to build terrain by using a text editor.
The coordinate system is Cartesian oblique, with the y axis tilted to
form a 60-degree angle with the x axis, so it can be difficult to relate
typed-in characters to the final appearance.  Landforms in the file
should appear to be leaning to the left, if they are to appear upright
during play.  However, sometimes text editing is necessary, for instance
when you need to change every instance of a terrain type to something
else.  (Incidentally, some of the large real-world maps in the library
were produced by coding all the terrain types from an atlas onto graph
paper, typing them in, then fixing the tilt as described above.)

Incidentally, areas should have some distinguishing terrain around the
edges; this prevents player confusion that sometimes happens when there
is no other clue as to where the edge might be.  However, this is not
enforced by @i{Xconq}, and you can put whatever you like along the
edges.  Randomly generated worlds normally use the value of the global
variable @code{edge-terrain}.

@node Synthesizing World Terrain
@subsection Synthesizing World Terrain

The random way to get terrain for a world is to use one of several
synthesis methods built into @i{Xconq}.

Totally random terrain is available via the synthesis method
@code{make-random-terrain}.  This just randomly chooses a terrain type
for each cell, using the weights in the @code{occurrence} property of
each type.  An @code{occurrence} of 0 means that the type will never be
placed anywhere.  This method produces a sort of speckly-looking world,
and is better for testing than for actual play.  Still, if you have two
types @code{vacuum} and @code{solar-system}, then a form like
@example
(add (vacuum solar-system) occurrence (20 1))
@end example
will give you a nice starfield for a space game.

The fractal world method @code{make-fractal-percentile-terrain} descends
from the most venerable part of @i{Xconq} (it was once a piece of Atari
Basic code).  It uses a fractal algorithm along with percentile-based
terrain classification to make realistic-looking worlds with terrain and
elevations.

To use this method, you first specify how many, what size, and what
height of blobs to splash onto the world, and how many times to average
cells with their neighbors.  Then you specify the subdivision of all the
possible altitudes and moisture levels into different kinds of terrain.
For instance, desert in the standard terrain ranges from sea level
(@code{alt-percentile-min} = 70%) to high elevations
(@code{alt-percentile-max} = 93%) but only in the lowest percentiles of
moisture (@code{wet-percentile-min} = 0%, @code{wet-percentile-max} =
20%).  It is important that all percentiles be assigned to some terrain
type, or the map generator will complain and subsitute terrain type 0
(the first-defined type); when designing terrain percentiles, it is
helpful to make a chart with altitude percentiles 0-100 on one axis and
moisture percentiles on the other.  Note that overlapping on this chart
is OK, and the terrain generator will pick the lowest-numbered terrain.
Also note that you don't have to include every terrain type.

The @code{alt} numbers are also used to compute elevations for games
that need them, but the @code{wet} numbers need not have anything to do
with water at all; they could just as easily represent smog levels or
vegetation densities.  If you only want to use one of the two layers,
just set the percentiles for the other to be 0 - 100 for all terrain
types.

[should have an example]

The method @code{make-maze-terrain} produces a maze consisting of a mix
of ``solid'', ``passageway'', and ``room'' terrain.  It uses the
@code{maze-room-density} and @code{maze-passage-density} properties of
each terrain type to decide how much of each to use for rooms and
passages.  The method first does random terrain generation, using the
@code{occurrence} property to decide how much of each terrain to put
down (remember that @code{occurrence} defaults to 1 for all terrain
types).  Then it carves out rooms, and passageways between them.  The
passages and rooms are guaranteed to be completely connected.

The method @code{make-earth-like-terrain} attempts to model the natural
processes and generate terrain as similar as possible to what is
observed on Earth today.

You should note that at least one method for synthesizing terrain must
be available, unless you can guarantee that terrain will be loaded from
a file.  The following subsections describe optional additional
synthesis methods that you can include.

@node Rivers
@subsection Rivers

You can use the @code{make-rivers} method to add rivers to the world.
Rivers are basically water features that depend on terrain elevations,
so they won't be generated unless both a river terrain type (either
border or connection) and elevation data is available.  You get them by
specifying a nonzero chance for some type of terrain to be the location
of a headwater (@code{river-chance}).

@i{Xconq} doesn't have any intuition about the behavior of water; it
will happily trace rivers all the the way down to the bottom of the sea.
Use the @code{liquid} property to tell @code{make-rivers} what types
that rivers cannot touch.  The method still traces the river's course,
and resumes modifying terrain when possible, which means that the river
can appear as both the inlet and outlet from a lake.

@node Roads
@subsection Roads

The @code{make-roads} method is a fairly generic method.  It just picks
pairs of units randomly and runs a road between them, attempting to
share road segments and route through favorable terrain.  Although
simplistic, the results look pretty good.

You can make short bridges by tweaking the road density appropriately.
Just allow roads from land to water, and water to land, but not from
water to water.

Note that this method is only useful if there are actually units for the
roads to connect.

@node Independent Units
@subsection Independent Units

For many games, it is useful to have independent units scattered randomly
across the world.  For instance, gold mines and treasure hoards would be
good for an exploration game, and independent castles for a medieval game.
You can set this up with the @code{make-independent-units} method.

@node Altitudes and Elevations
@subsection Altitudes and Elevations

@i{Xconq} is basically a 2-dimensional game, but you can emulate a third
dimension by defining elevations for terrain and altitudes for units
above and below the terrain.

The main use of altitudes is to control interactions between certain
kinds of units, particularly aircraft.  For instance, a high-altitude
bomber should be able to pass over a ship and under a satellite with
impunity.  In general, you define the ``operating altitudes'' of a unit,
so in the example above, you could say that a ship is always at the
surface, bombers operate at 1-10 km, and satellites at 100-10,000 km.
If a unit has more than one operating level, then it can move up and
down by normal movement actions.

Also, most details such as speed and material consumption are the same
for a unit at any altitude.  (Yes, such things vary in real life, but
the effects are usually minor within the unit's normal operating range.)
 
Altitudes have a significant effect on combat.  A unit at some altitude
can only attack units at a specific range of altitudes up and down.
Using the example again, you could define fighter aircraft to operate at
0-20km and be able to attack up and down 5km, while bombers can attack
up to 10km down (i.e. down to the ground), but not up.  Satellites
remain invulnerable.

All this applies equally to units underground and undersea.

[need info about setting up other layers]

@node World Setup Miscellany
@subsection World Setup Miscellany

For additional flavor, with no effect on game play, you can identify
and name geographical features in the world.

For predefined areas, just add the @code{features} layer and either fill
in manually, or with a design tool.  I find that the most efficient
approach is to make a list of all the features that I want to be in the
world, set up the list manually along with layer data saying that all
parts of the area are unnamed (all 0s), then read in the world + feature
layer and use the online feature painting to define the shape of the
feature.

For random areas, the synthesis method @code{name-geographical-features}
does the work.  You can use a side property @code{feature-namers} and a
global variable, also called @code{feature-namers}.  Both of these map
feature types to namers (for ``namers'', see below).  The list of types
of features to try to identify is in the global @code{feature-types}.
The basic idea is that the synthesizer looks for the types of features
requested, then names them using the appropriate namer.

Here is what the standard game does to generate funny names for lakes,
but the more-anonymous "Peak 4532" for mountain tops:
@example
(set feature-types (("peak") ("lake")))

(set feature-namers (("lake" "generic-lake-names")))

(namer generic-lake-names (grammar root 10
  (root (or 5 (foo "Lake " generic-names)
            1 (generic-names " Lake")
            ))
  (foo "")  ; works around a bug
  ))

(include "ng-weird")
@end example

@node Designing the Sides
@section Designing the Sides

Sides represent the players in a game.  They also serve as a repository
of information shared by units, such as technology and knowledge of the
world.

You should first decide how much about the sides will be predefined.  If
you're doing Eastern Front scenarios, it's very easy; you have Russians
and Germans and that's it.  If you're doing a science-fiction
empire-building free-for-all, you may not have to specify anything more
than a random side name generator.

@menu
* Predefined Sides::            
* Side Library::                
* Limits on Sides::             
* Hints on Sides::              
@end menu

@node Predefined Sides
@subsection Predefined Sides

For scenarios and similarly-restrictive games, the game design should
create the sides directly, as in this example:
@example
(side (name "Germany") ... (colors "black,gray") ...)

(side (name "Russia") ... (colors "red") ...)
@end example

Since the initialization machinery allows matching any player with any
side, you can get away with being really vague.  This will create four
sides but not say anything about them:
@example
(side)
(side)
(side)
(side)
@end example

If you're going to have predefined units on each side, then you should
add an id to each side:
@example
(side 1 (name "Germany") ... (colors "black,gray") ...)

(side 2 (name "Russia") ... (colors "red") ...)
@end example
Instead of @code{1} and @code{2}, you can also use, say, @code{ge} and
@code{ru}; ids can be either symbols or numbers.

@node Side Library
@subsection Side Library

If your game design does not predefine all the sides, you can define a
@dfn{side library} using the @code{side-library} variable.  Basically
the library is a weighted list of collections of side properties, each
formatted as a side definition.  @i{Xconq} will use this library for any
player that is allowed in the game but who does not have a side already,
and select a side with a probability determined by the weights.  Each
item in the library will be used up to a limit that can be specified
with each item; if the library has been exhausted before all the sides
have been created, then the extra sides will just be assigned general
defaults for their properties.

The side library here makes futuristic sides for players, making two of
the sides most likely, but allowing others as well:
@example
(set side-library '(
  (10 (name "Federation") (adjective "Federation") (class "fed"))
  (10 (name "Klingon Empire") (noun "Klingon") (class "klingon"))
  (5 (noun "Romulan") (class "romulan"))
  ((noun "Ferengi") (class "fed"))
  ((noun "Vulcan") (class "fed"))
  ))
@end example
Note that if the game design limits certain unit types to certain sides,
the choice of sides will be more than just a cosmetic issue.

@node Limits on Sides
@subsection Limits on Sides

So that you can put upper and lower bounds on the number of sides in your
game, GDL includes the variables @code{sides-min} and @code{sides-max}.
As you might expect, every game design must allow at least one side.
The upper limit on sides depends on the implementation, but is at least 7.
Large numbers of sides can make a player's life very complicated,
not to mention consuming vast quantities of memory, so you should
try to limit the number of sides as much as possible.

Another important limit is based on the notion of @dfn{side classes}.
Each side can have a side class, and multiple sides can belong to the
same class.
For instance, sides named @code{"Hyperborean"} and @code{"Germanic"}
could both have class @code{"barbarian"}.
The value of side classes is that unit types have a property
@code{possible-sides} that limits which side class(es)
a type can belong to.  This is very important for any game
in which different players should have fundamentally different
sorts of units.  To continue the barbarians example, it is basically
impossible for any barbarian side to have even one Roman legion,
whether by construction, capture, or even surrender.
So you can do something like
@example
(add legion possible-sides "roman")

...

(side 1 (name "Rome") (class "roman"))
(side 2 (name "Germania") (class "barbarian"))
(side 3 (name "Hyperborea") (class "barbarian"))
@end example
and ensure that Roman legions are always Roman.

@node Hints on Sides
@subsection Hints on Sides

Note that players tend to identify with the sides they're playing,
so a game should allow for as much personalization as possible.
On the other hand, some scenarios derive part of their flavor from
predefinitions.  For instance, a scenario with sides named
``German'' and ``Russian'', with appropriate colors and emblems,
doesn't have quite the same feel when players rename them to ``Subgenii''
and ``Simpsons''.

A side can have a huge amount of state data, such as the current view.
This rarely needs to be included in its entirety; synthesis methods
will usually suffice to set view data correctly.
Since total security is impossible with a predefined world,
setting a side to have only a partial view won't necessarily
be useful to keep players from knowing what that world really looks like.

@node Setting up the Units
@section Setting up the Units

Once you've decided how to handle sides in your game, you can move on to
the initial unit setup.  Initial unit setup is very important, since it
has a major bearing on how the rest of the game will go, and can be done
in a number of different ways.

@menu
* Predefined Units::
* Making Countries for Players::
* Initial Supply::
@end menu

@node Predefined Units
@subsection Predefined Units

GDL allows you to define everything about every starting unit in the
game.  This is a powerful approach, but requires much preparation.  An
advantage of predefined units is that there are no unpleasant surprises.
For instance, suppose you designed an empire game with ships and cities,
but a random setup leaves some players entirely landlocked.  Not only
will those players be @emph{very} unhappy, they might come looking for
you @i{before} they've calmed down!

Asking for initial units is pretty easy, you can either type them into
a file or create them directly, using the appropriate designer tool in
a game.
@example
(city)
(city 11 12 1)
(city (n "Brigadoon"))
(city (@@ 10 10) (n "New York"))
(city (@@ 20 10) (n "London") (hp 22))
@end example
The only info that you absolutely have to supply is the unit's type.  If
the position is missing, the unit will be placed at a random location.
If the side number/name is missing, the unit will be independent or on
the first possible side.

While the type, position, and side of units is important, exact values
of the other properties are rarely important for a scenario.  Also, a
unit with fewer filled-in properties can be used in different games.
For instance, a list of the present-day major cities worldwide really
needs only name and location for each; the game design can fill in
everything else.  One way to do this would be to set up an appropriate
@code{unit-defaults} just before including the module.

To make units start inside transports, you need to specify the @code{t#}
property for the occupant, and have its value be the id number or name
of some other unit.  Your players may get an error message if the
occupant is not of an allowed type for the transport to hold.

@node Making Countries for Players
@subsection Making Countries for Players

Despite the advantages of predefining initial units, this doesn't help
when you want variable groups of units to appear in a randomly-generated
world.  Instead, you should use the @code{make-countries} synthesis
method.  The basic idea is that the method picks a good location for
each side's country, scatters an initial set of units around that
location, then possibly grows the country outwards.  You can do anything
from small widely-separated countries to an interlocking nightmare
resembling pre-Bismarck Germany.  Because of this, and because of the
requirement that this method generate random setups that are as fair as
possible, you have a great many parameters to work with.  These
parameters should be tuned carefully - you will probably need to
generate and study lots of initial setups, especially if your parameters
constrain the countries very tightly; the method cannot backtrack to fix
a poor combination of placements.

The first step in country generation is to select a location for each
side's country.  The location is a point that is the ``center'' of the
country (the exact value will be unimportant to players, and is not used
outside this method).  The constraints are that the center of each
country is farther than @code{country-separation-min} from the center of
every other country, that the center is within
@code{country-separation-max} of at least one other country, and that
the given initial area of the country (as defined by
@code{country-radius-min}) includes numbers of cells of each terrain
type bounded by @code{country-terrain-min} and
@code{country-terrain-max}.

The reason for the separation constraints is that having countries too
close together or too far apart can create serious problems.  Consider
the poor soul who gets tightly sandwiched between two enemies, thus
becoming lunchmeat, ha ha, or the not-quite-so-poor-but-still-unlucky
player who ends up on the wrong side of a very large world.  (Keep in
mind that your players may ask for a much larger world than you were
thinking of when you designed the game.)

The terrain constraints help you put the country in a reasonable mix of
terrain.  For instance, if you want to ensure that your countries
include some land, but be on the coast rather than inland, then you
should say that the country must have a minimum of 1 sea cell and 1 land
cell.  (In practice, the values should be higher, so you don't get small
islands being used as entire countries and lakes being considered the
ocean.)  Keep in mind that these constraints may be impossible to
satisfy, for instance if a particular world does not have enough of the
sort of terrain that is being required in a country.  If the basic
placement constraints fail, @i{Xconq} will just pick a random location,
warn about it, and then leave it up to the players to decide on whether
to play the game ``as it lies''.
@example
;;; Keep countries close together, but not too close.

(set country-separation-min 20)
(set country-separation-max 25)
@end example

Once @i{Xconq} has decided on locations for each country, it then places
the initial stock of units.  You define this initial stock via the unit
properties @code{start-with} and @code{independent-near-start}.  The
@code{start-with} units start out belonging to the side, while the
@code{independent-near-start} units are independent.  The locations of
these units are random within @code{country-radius-min} of the center,
but are weighted according to the table @code{favored-terrain}.  This
table is very important; it is the percent chance that a unit of a given
type will be placed in terrain of the given type.  100 is guaranteed to
work, and 0 is an absolute prohibition.  Since @code{make-countries}
tries repeatedly to place each @code{start-with} unit until it succeeds,
then even terrain with a @code{favored-terrain} value of only 10% will
get used if there is no other choice, so the table affects the
distribution of units rather than the number that get placed.  If a
starting unit cannot be placed on any available terrain, but can be an
occupant, then @i{Xconq} will attempt to put it inside some unit already
present.  This is a good way to begin a game with aircraft at airports
rather than in the air.

The upshot is that all this will do a reasonable layout if the
parameters are set reasonably.  If, however, @code{favored-terrain} is
never > 0 for the @code{start-with} units and the country terrain, but
there is some other terrain type for which this would work, @i{Xconq}
will change the terrain.

This example is from the ``classic'' @i{Xconq} game:
@example
(set country-radius-min 3)

(add city start-with 1)
(add town independent-near-start 5)

(table favored-terrain 0
  ((town city) plains 100)
  (town (desert forest mountains) (20 30 20))
  )
@end example

The net effect is to give each player one city outright and 5 towns
nearby.  Although created independent, these towns can be easily taken
over right at the beginning of a game, so they are a kind of ``warmup''
(like the pushing of pawns at the beginning of a chess game).  The
@code{favored-terrain} table allows cities to appear only in plains,
while giving more options to towns, since they can appear in deserts,
forests, and mountains.  Even so, towns are 5 times more likely to be in
plains, which is reasonable.

In addition to defining a country by placing units, you can also have
the synthesizer add people to the country.  People in the country don't
usually have a lot of effect on a game, but are useful for heightened
realism.  You can have people on your side report on units passing
through their cells by setting @code{people-see-chance}.  To set up
people, use @code{country-people-chance} to define the probability
of terrain in your country getting people.  For most games, you will
want to set this to a high probability for land types, and to 0 for
sea terrain types.

The optional last step in country generation is to grow the countries
outwards from the initial area.  This is basically a simple simulation
of the historical forces that give countries their variety of shapes.
You enable this by setting @code{country-radius-max} to a value greater
than the minimum country radius.  The algorithm works by deciding
whether to add to the country each cell at each distance from the
country's center.  The chance depends on the terrain type (via the
terrain property @code{country-growth-chance}) and whether the cell has
already been given to another country.  If the cell belongs to another
country already (as detected by looking at its people), the algorithm
uses @code{country-takeover-chance} to get the probability of change.
Once a cell has been given to the country, then the method decides
whether to add a sided or independent unit to the cell
(@code{unit-growth-chance} and @code{independent-growth-chance},
respectively), or whether to change the side of an existing unit
(@code{unit-takeover-chance} and @code{independent-takeover-chance}).
Country growth stops when the absolute maximum radius has been reached.
However, you can make it stop early if no cells are being added to the
country, by setting @code{growth-stop-chance}.

This example is from one of the variants of the standard game:

@example
(game-module "standard"
  ...
  (variants
   ...
    ("Large Countries" eval
     (set country-radius-max 100)
     )
  ))
@end example

The resulting effect is to make all the countries border on each directly.

@node Initial Supply
@subsection Initial Supply

In games involving materials, you have to decide how much will be in the
game at the beginning.  If materials are at all significant (and if
they're not, why include them in the game?), then you need to ensure
that the initial amounts are set up correctly.

The key table for this is @code{unit-initial-supply}.  By default, all
units start out empty of all supplies.  This may not be a good default
for materials that units consume, however; if the production process is
too slow, then your initial units may starve at the beginning of the
game.  This can be especially annoying if the initial units starve only
because they ended up on less-favored terrain.  To avoid this, you can
add a clause like @code{(u* m* 9999)}, which, if material capacities are
all less than 9999, causes initial units to start out full.  Note that
this applies to all units, irrespective of side.

In addition, if you want your game to be based on resource extraction,
you can also set @code{terrain-initial-supply} to give amounts of
materials to each cell in the world. [mention exhausted-type here?]

@node Setup Miscellany
@section Setup Miscellany

This section describes random things.

@menu
* Technology::
* Setting up Self-Units::
@end menu

@node Technology
@subsection Technology

Technology, or tech for short, is useful when technological development
is important to a game.  There are several ways to use it.

One use of tech is to track the results of research.  You do this by
setting the initial tech of a side to (say) 0, then requiring a certain
tech (say 60) in order to build a desired type.  If a research action
adds 1 to a side's tech, then it will take 60 research actions to gain
the necessary level.  The number of turns, of course, depending on how
many actions the researcher can do each turn, and how many researchers
are available.  So for instance, 10 researching units results in the
work being done in 6 turns instead.  You can limit this schedule
acceleration by setting @code{tech-per-turn-max}.

Another use of tech is to differentiate sides.  Suppose you want to do a
game involving earthlings and space aliens.  The aliens can have
satellites overhead that earthlings don't even know are there, they have
equipment earthlings couldn't use even if they were able to capture it.
However, earth scientists might learn something from it.  To do all
this, use @code{tech-to-see} and friends.

Tech is fundamentally tied to unit types.  However, many games have a
number of unit types that share technology.  For instance, advances in
bomber technology usually lead to advances in fighter and surveillance
aircraft.  The @code{tech-crossover} table is available for this
purpose.

@node Setting up Self-Units
@subsection Setting up Self-Units

Normally a player runs the side as a whole, and all the units on that
side are disposable and interchangeable.  However, you require one unit
to represent the player personally among the units of the player's side;
this unit is the @dfn{self-unit}.  What this means is that if that unit
is captured or dies, the player loses the game instantly.  All the other
units on the side will behave normally as for losing, either going over
to the side that captured the player, becoming independent, or
disbanding.

The idea is to increase the player's motivation for self-preservation.
This is useful to introduce a risk of capture, assassination, and so
forth.  It also prevents bizarre and unrealistic strategies in some
games.

For instance, it sometimes happens in empire-building games that players
end up switching countries, because each captured another's country and
neglected to defend their own.  If each player got one capital city, and
that city were to be a self-unit, then the owner would have to defend it
at all costs!

To make this happen, you could do something like this:
@example
(set self-unit-required true)

(add capital-city can-be-self true)

(add capital-city start-with 1)
@end example

@node Units and Actions
@section Units and Actions

Players can do all kinds of things with their units.  They can push
the units around, they can make units build things, they can get into fights,
or they can just let them sit around.
You as the designer decide which kinds of things make sense in your
game, then set up the action parameters appropriately.
Is moving through swamps going to be slow?
Can a small town build any kind of ship, or just small ones?
How often can Godzilla breathe fire?

Now, what the players work with is the interface, which can do all
kinds of intelligent things -- whatever makes sense for that interface.
However, no matter what the interface, no matter what kind of play
automation, player input eventually breaks down into unit actions.
The set of action types is predefined and can't be changed.
They are also very primitive.  Each action takes a number of arguments,
such as the type of unit to build or the location to move to,
the action just happens and either succeeds or fails on the spot.
There are no actions that take longer than one turn to complete,
and a unit can perform only one action at a time.
This may seem horribly restrictive, but actions are just
the low-level building blocks;  players rarely see actions directly.
You have to be aware of them because the game design specifies
which unit types are capable of which actions.
Each @i{Xconq} interface will adjust itself to disallow input that
would result in types of actions that you have prohibited.

The number of actions that a unit can do in one turn is limited
by its action points.  A unit with zero action points cannot do anything
at all.  A unit with lots of action points can do lots of actions,
unless each action costs many action points.
You can define the action point cost of each type of action for each
unit type.  In some cases, the cost will also depend on the action's arguments.

Acp is actually a little like a bank account,
since by not doing anything for awhile,
a unit can accumulate extra acp (up to @code{acp-max}),
and it can go into debt temporarily, down to @code{acp-min}
(which may be a negative value).
A unit in ``action debt'' at the beginning of a turn cannot move
or do anything else, and must wait for a turn
when its acp goes positive again.  This can be a simple way to implement
both fatigued units and units that can do more if they plan for it.

Actions always include both an actor and an object.  The actor is
the brains, and that is whose acp gets used up, but the object has the
action actually happen to it.  This is so animate units (like humans)
can manipulate inanimate units (like swords).  You enable this by setting
the acp of the inanimate to zero, but requiring nonzero acp in the various
@code{acp-to-} tables.

In most cases, the actor and actee are the same unit.

@node Unit Movement
@section Unit Movement

Movement is the most important action type.  There are actually two distinct
types of actions; one to enter a cell, and one to enter a unit.

Each unit has a speed which is determined at the beginning of the turn
and determines how many cells it can enter during the turn.
However, terrain, borders, and other obstacles can consume extra
movement points.

@menu
* Unit Speed::
* Movement Costs::
* Entering Transports::
* Border Slides::
* Leaving the Area::
* Free Moves::
* Zone of Control::
@end menu

@node Unit Speed
@subsection Unit Speed

Units have a base speed @code{speed} which is the ratio of mp to acp.
You can set damaged units to move more slowly.
You can also allow occupants to add to the speed, up to the
@code{speed-max} limit.

You can define wind-affected units by defining speed in each direction
(max-speed only, do others proportionally).  Would need 4 distinct mp costs
plus a formula to relate to wind strength.  Wind speed defined as "how
far a particle of air moves in a turn".  Unit examples include balloons,
dirigibles, sailing ships, floating cities.

@node Movement Costs
@subsection Movement Costs

Typically the cell entry cost will be the most useful to adjust,
although the departure cost can be useful in representing units
mired in jungle mud
and taking a long time to escape onto clear terrain.

Be aware that complicated entry/exit costs are confusing to players,
and AIs may not take them into account very well either.
Using @code{free-mp} helps players use up all their acp.

@node Entering Transports
@subsection Entering Transports

Different kinds of transports have different ways for units
to get on and off.  For instance,
ships can dock, or use their boats to enable land units to get on and off.
The tables @code{ferry-on-entry} and @code{ferry-on-departure}
specify how much terrain units will have to cross on their own.

[example]

Observe that enter/leave costs can be used to make one-way trips.
For instance, paratroops jumping out of a plane should be able
to leave cheaply, but have an entry cost so high that they can
only reboard in a later turn.

@node Border Slides
@subsection Border Slides

One of the problems with @i{Xconq} borders and connections is that
neither works exactly like a sea strait.  Consider the Straits of
Gibraltar.  They are so narrow that one can see the other side,
but nevertheless impose a formidable barrier to landlubbers.
At the same time, ships can pass through readily, if
not secretly.  If cells in the world are 60 miles across, then
making an all-sea cell is a gross exaggeration.
However, adding a water border only prevents both land and sea movement!
To get around all this, @i{Xconq} allows a special kind of
move called a ``border slide''.
Basically, if both the destination cell and the border whose endpoints
touch the start and end cells are allowable terrain for a unit,
then the unit can move to the destination cell in one move.
However, it incurs a special cost in addition to the normal entry
and leave costs for the terrain in the two cells (but @i{not} the border
crossing cost, since the border is not being crossed, exactly).
This cost is in the table @code{mp-to-traverse}.
Border sliding should usually be somewhat expensive, both because
of the distance (the unit ends up two cells away after only one move),
and because of the real-life difficulties of passing through a narrow
strait.  Note that border sliding does not escape the units on either
side of the border, since the unit doing the sliding will still be
adjacent to the cells on each side of the border it slid through.

@node Leaving the Area
@subsection Leaving the Area

This feature can be useful in allowing a non-disbandable unit type
to escape capture or otherwise retire from action.

@node Free Moves
@subsection Free Moves

This is most useful in emulating some board games,
or to prevent clever players from exploiting a mess of move costs.
The default of @code{-1} is the most playable,
since player will always be able to use all of their mp.
Otherwise, there may be situations in which a unit has
a few acp left, but not enough to go anywhere,
and so they end up being wasted.
The free move does not actually get subtracted from the unit's acp,
it just doesn't let lack of acp forbid the move.

@node Zone of Control
@subsection Zone of Control

Sometimes a unit can by its presence alone affect the movement of unfriendly
units in the vicinity, perhaps by requiring them to hide or to move
carefully in order to pass by, or even to prevent entry altogether.
This is called the ``zone of control'' or ZOC.

Exerting a ZOC requires no action, nor any particular capability on
on the part of the unit exerting the ZOC.  For instance, a toothless
fort could still cause raiders to sneak by carefully (at least if they
didn't know that it was toothless).

@node Unit Construction
@section Unit Construction

Construction is very important to empire-building and similar strategic
games.  The construction of a unit may involve as many as four different
kinds of actions.  This is so you can make construction be an expensive
long-term process.

The basic construction is unit creation.  A player might have to do
research and toolup actions in order to prepare for creation, and might
also have to do completion actions, if the created unit is not ready to use.

Normally the interface will just have a single "Build <type>" command,
which then results in a task that issues appropriate actions, so players
don't necessarily see all these different actions.
 
@menu
* Researching::
* Tooling Up::
* Creation::
* Completion::
* Repair::
@end menu

@node Researching
@subsection Researching

Some types of units may be relatively easy to build, once you know how,
but at the same time that type totally changes the balance of the game.
The atomic bomb in WWII is the classic example; once it became available,
everything changed.

To allow research, set @code{acp-to-research} to 1 or more.

@node Tooling Up
@subsection Tooling Up

Toolup costs are what you use to represent the overhead of changing
construction.  Quite often it does not need to be set.  Its primary
use is to encourage players to commit to grand strategy once chosen,
because the cost of changing would be prohibitive.

@node Creation
@subsection Creation

You enable creation of new units by setting @code{acp-to-create}
to 1 or more.
The location of the newly created unit will depend on both the
types involved and how the interface works, since both @code{create-in}
and @code{create-at} actions are available.
For instance, the new unit immediately takes up space,
so if creating unit is already full, then the interface
should have issued a @code{create-at} action to put the
new unit outside the creator but still stacked in the same cell.
If this is still too restrictive, and you want to allow players
to create units in nearby cells, you can set @code{create-range}
to values higher than the default of 0.

In order to represent the material costs of creation,
you can set a minimum requirement, via @code{material-to-create},
and an amount to be consumed, via @code{consumption-on-creation}.
You could think of @code{material-to-create} as representing
catalysts or work force, while @code{consumption-on-creation}
is the raw material that becomes part of the new unit.

Finally, you can set the @code{supply-on-creation} to have
@i{new} material created and given to the new unit.
This is useful for abstract materials (such as ``enthusiasm'')
that are somehow ubiquitous.  You should be careful with this
one, because if the new material is transferrable between units,
then players could collect a stockpile of the material by
creating units, stealing their supply, and never finishing them.

@node Completion
@subsection Completion

By default, newly created units are complete and ready-to-use.
This is rarely a good idea in a game design,
since even 1 acp-per-turn creators can then create
another brand-new unit on each turn.
If you're going to allow that, then you
should include something else to keep players from being swamped by
overpopulation.  You can set high accident or attrition rates,
make creation require scarce materials,
or make the creators be scarce.

The best way to slow down unit creation is to create incomplete
units and then require @code{build} actions to finish them.
Completeness is defined
in terms of completeness points (cp) that you can set for each
type.  A build action then just adds to completeness points.
Incomplete units do in fact exist as units, so for instance they
can be captured and completed by another side.

As with creation, you have to set @code{acp-to-build} to
1 or more just to enable build actions.

In order to regulate the rate of completion, you have to
set the @code{cp} of the unit types being constructed,
which defines the point at which the unit will be complete,
and then fill in @code{cp-on-creation} and @code{cp-per-build}.
The most straightforward approach is to set @code{cp}
to be the number of turns you want to have between each unit
being constructed, then let @code{cp-on-creation} and
@code{cp-per-build} both be 1.

You can set @code{build-range} so that several units can
cooperate to accelerate construction of a unit.
There are no maximum rate limits set on this, but it's
unlikely that players will ever be able to achieve much
acceleration, because of the limit on the distance between
the builder and the unit.  For instance, the default range
of 0 implies that multiple builders of a unit have to be in
the same cell, which may in turn be constrained by stacking
limits.

As with creation, you can also set values in @code{material-to-build}
and @code{consumption-per-build} to govern material requirements
and usage.

You can also allow units to complete themselves.  For instance,
large ships often use part of their soon-to-be crew to help finish
the last stages of fitting out.  You set this up via @code{cp-to-self-build}
and @code{cp-per-self-build}.  Since incomplete units are incapable
of doing any actions, this is a totally automatic process that happens
at the beginning of each turn.  Self-building and normal building can
proceed simultaneously, so you can use this to accelerate the final
stages of construction.

Finally, newly completed units can have materials created for them,
as defined by @code{supply-on-creation}.

@node Repair
@subsection Repair

Players' units will inevitably become damaged, whether in combat,
from accidents, or from other causes.

There are two ways that units recover hp; either automatically,
as defined by @code{hp-recovery}, or by the explicit action @code{repair}.
Automatic recovery is good for that part of damage that a unit can
fix just by the passage of time.  It's always good for playability, since
a player just needs to ``rest'' the unit in order for it to get better.

On the other hand, the decision to repair may need to be a difficult
one, and impact both tactical and strategic planning.  For instance,
a badly damaged battleship can choose to go on fighting and risk being
sunk, or withdraw for repairs and perhaps jeopardize the campaign it is
supporting.

In such cases, you can allow explicit repair actions, via the table
@code{acp-to-repair}.  You can set the repair rate via
@code{hp-per-repair}.
You can also specify how healthy the
repairer must be, via @code{hp-to-repair}.
Units can repair themselves.

@node Unit Combat
@section Unit Combat

Not all games require fighting.  Races and exploration
can be lots of fun, and don't require players to be bashing each other.
However, the excitement of most @i{Xconq} games derives
from the chances of going up against an opponent directly.

Combat includes five distinct action types that a player may choose
from, not counting detonation, and you specify the characteristics
of each.  ``Attack'' is hand-to-hand with another unit, ``capture''
attempts to change the side without damaging, ``fire-at'' hits a unit
without getting entangled, while ``fire-into'' hits everything
in a targeted cell.
Finally, ``overrun'' is an attempt to occupy a cell, doing whatever
combination of attack, capture, and movement is necessary.

To specify what kinds of battles are possible, you begin by setting
the @code{hit-chance} of some unit vs another unit to any value
greater than zero.  A hit probability of zero completely disallows
attack.  A hit probability of 100 is a guaranteed hit.
In practice, you will probably need to specify most hit probabilities
individually.

[describe mods to hit prob?]

Next you need to set the damage done by a hit.
The default value is 1 hp, which is a good starting place
but not always particularly realistic.

[describe variation parms]

As usual, you can define the action point cost of combat,
via @code{acp-to-attack} and @code{acp-to-defend}.
The use of separate tables for attacker and defender allows for
some extra flexibility.  This is important, because sometimes you
want to allow combat to keep a defender busy and soak up its acp,
while at other times attempts to engage in combat should be shrugged off.
Consider battleships vs infantry; although combat between the two
rarely causes much damage, an attack by a battleship will cause the
infantry to keep their heads down, and preventing them from doing much else,
while the return rifle fire is unlikely to disturb the battleship much!

Describing simple hit probabilities and damage is oftentimes sufficient
for a game.  It's simple; players can learn the numbers by heart.
It's more efficient, because there's no need to manage lots of
ongoing battles.  However, there are endless numbers of situations
where this basic model is unsatisfactory, so let's move on to the
available enhancements.

The basic parameter for the firing actions is @code{range} of the unit,
which is the greatest reach possible.
You can also set a @code{range-min}, which is useful for ballistic
missiles, certain kinds of artillery,
and magic spells that can't be used for close-in fighting;
you can't fire at a unit that is less than @code{range-min} cells away.

Also, you can define how transports and occupants affect each other in
combat.  The effects can be both positive and negative, and extend both
from occupants to their transport and from the transport to its occupants.
The table @code{transport-protection} defines the percentage of hit damage
(by any unit type) that gets passed through to each occupant.
If 0, then the transport is perfect protection. If 100, then each occupant
gets the same hit as the transport did.
[Ideally, protection is a prorating on a table value from occupant vs attacking
unit.]
Note that an occupant cannot be attacked directly from outside its transport.

If you want to make combat dependent on having a supply of ammo, use the
tables @code{hit-by}, @code{material-to-attack}, @code{material-to-fire}, 
@code{consumption-per-attack}, and @code{consumption-per-fire}.
The material type need not be explicitly designated as ammo,
but both the hitting and hit units must agree that the same type
is effectual (we assume that the attacking unit is smart enough not to
use material types that have no effect on the target unit).

[need a combat-supply usage in addition]

@menu
* Capture::
* Detonation::
@end menu

@node Capture
@subsection Capture

Capture is both a distinct action type and a possible consequence of
normal combat.  As an action, it is useful for both ``bloodless''
captures and the collecting of objects from a dungeon floor.

To allow explicit attempts to capture, set @code{acp-to-capture} to 1 or
more.

Whether the capture attempt is explicit or a consequence of combat, its
basic probability of success is derived from the table
@code{capture-chance}.  If the unit being captured is independent, there
is a separate table @code{independent-capture-chance}; if its value is
the default of -1, then the value of @code{capture-chance} will be used
instead.

For capture attempts that are going to succeed, you can allow the victim
a chance to wreck itself first, by setting @code{scuttle-chance}.

The main effect of capture is simply to change the side of the unit that
was captured.  If the unit cannot be on the capturing side, then it will
vanish instead.  In any case, the occupants will also be captured or
vanish, although you give them a chance to escape first via
@code{occupant-escape-chance}.  They will also attempt to scuttle
themselves if possible.

You can also require a sacrifice from the capturing unit, via the table
@code{hp-to-garrison}.  This is the number of hp that will be taken from
the capturing unit.  You can set it to the unit's @code{hp-max} to make
it disappear entirely.  Although this table is inspired by realism, it
can also serve a pragmatic purpose, namely to prevent a single unit from
capturing an entire country without being affected at all!  You should
set this table according to the ``feel'' you want for the game, since it
can have a major effect on speed and pacing of the play.

As with normal combat, the experience of both the capturing and captured
unit may change.  For the capturing unit, this is a gain defined by
@code{cxp-per-capture}, while the effect on the capturing unit is set by
@code{cxp-on-capture-effect}, which is a multiplier (defaulting to 100)
that may increase or decrease experience.  In practice, a decrease is
more realistic, representing perhaps the replacement of ship or airplane
crews, although a increase might be more appropriate for mercenaries
whose response to capture is simply to go to work for the new bosses!

@node Detonation
@subsection Detonation

Detonation is both a type of action @code{detonate} and an automatic
behavior.

Detonation can damage both the detonating unit (though it need not) and
any units around its point of detonation, which may or may not be its
location.  You set it up by defining @code{acp-to-detonate} to one or
more, set @code{hp-per-detonation} to express the amount of damage done
to the detonating unit, then fill in the detonation damage tables
@code{detonation-damage-at} and @code{detonation-damage-adjacent} to say
how badly each type of nearby unit will be hit.  You can define the
exact radius of effect via @code{detonation-range}.  The effects on
occupants of nearby units will be adjusted according to the same
protection/ablation tables as for combat.

You can also set detonation to trigger on various kinds of events, such
as damage to the detonating unit (@code{detonate-on-hit}, death of the
detonating units (@code{detonate-on-death}), impending capture
(@code{detonate-on-capture}), and proximity of certain types of units
(@code{detonate-on-approach}).  You can also set a chance that a unit
will detonate spontaneously, via @code{detonation-accident-chance}.

In order to model the catastrophic effects of the worst explosives, you
can set @code{terrain-damage} to indicate how terrain types will change.

A minefield could be implemented by defining a detonating unit that
loses some small percentage of its hp every time a unit hits it, while
hitting the other unit automatically.

A simple trap would auto-detonate only once, then change to a ``sprung
trap'' type.  Then the right kind of unit could come along and do a
change type action to reset it.

@node Unit Manipulation
@section Unit Manipulation

The actions in this group are a mixed bag of manipulations.
If they need to be in your game, then the need will be obvious,
otherwise they are pretty much optional.

@menu
* Transferring Unit Parts Action::
* Changing Side::
* Changing Type::
* Disbanding::
@end menu

@node Transferring Unit Parts Action
@subsection Transferring Unit Parts Action

Any unit whose @code{parts-max} is greater than the default of 1 is a
multi-part unit, and its hp denotes size rather than amount of damage.
Armies and fleets are two kinds of units which can be usefully defined
as multi-part.

Players will very often want to merge or detach parts of a multi-part
unit, and there is an action @code{transfer-part} provided for that.
You can control the cost of the action by setting
@code{acp-to-transfer-part}.

@node Changing Side
@subsection Changing Side

Side changing is like capturing, but players can only do it to units
that they control.  The action is @code{change-side}, and you enable by
setting @code{acp-to-change-side} to 1 or more.  This will also enable
side changing for units that cannot normally act.

Side changing is especially useful for alliances in multi-player games,
so it should usually be enabled.  On the other hand, it should not be
too cheap; you should consider what side changing really means in the
game's context.

For instance, even in the close British/American alliance during WWII,
armies never actually changed sides; British ground units were always
British, and American ground units always American.  On the other hand,
ships and bases could be traded back and forth with only a cost in time
and expense.

@node Changing Type
@subsection Changing Type

In some games, it will be useful to have a notion of promotion
or upgrade for units.  You can implement this by allowing players
to do a @code{change-type} action.

You enable this via the @code{acp-to-change-type} table.

@node Disbanding
@subsection Disbanding

Sometimes a player will want to get rid of a unit,
perhaps because some type has been overproduced and is tying up
valuable resources, or to prevent it from falling into enemy hands.

You can allow this by setting @code{acp-to-disband} to 1 or more.

You can control the rate of disbanding with @code{hp-per-disband}.
You may, for instance, want to allow the deliberate destruction
of large units, such as battleships, but you don't necessarily want
disbanding to be a convenient way of preventing their capture.
Setting @code{hp-to-disband} so as to require several turns to
get rid of a unit will accomplish this.
The table @code{supply-per-disband} will allow you to govern the
rate of recovery of the unit's supplies during the disbanding process.

It is also possible to make disbanding a way to recover materials
that were consumed in the construction of the unit, by using the
table @code{recycleable-material}.  Care should be taken that creation
and disbanding of units is not a convenient way to manufacture lots
of a material; players @i{will} use the loophole if it exists!

It should usually not be possible to disband something large like a city,
otherwise a clever player might try to eliminate it as a strategic target,
but most mobile units should be easily disbanded.
This is especially helpful in an ``construction spiral'' game, where
the winning player(s) can accumulate large numbers of useless units.

@node Material Manipulation
@section Material Manipulation

You can allow players to produce materials by explicit action,
and you can control how they transfer materials between units.

Note that you can usually have a reasonable game without requiring
all the players to become shipping clerks.  The automated production
and transfer parameters (see xxx) are almost always sufficient for
a game.  Explicit action should be limited to games where material
limitations are so severe that they impact strategy directly,
and players have to make hard choices between producing materials
and doing other actions, on a turn-by-turn basis.

You can define ``stevedore'' units by setting both rate and acp such that
the u1 -> stevedore -> u2 transfer is faster and cheaper
than the basic u1 -> u2 rate.
Then players can use the stevedores to speed up transfers.

@node Terrain Manipulation
@section Terrain Manipulation

In a few games, you will want to let players alter the terrain.
This needs to be done judiciously,
since a cell of terrain generally represents a vast area,
and the simulated time in @i{Xconq} is generally too short
for major terraforming operations.
However, building bridges and digging moats can be reasonable
additions to a game.

Since actions are always completed quickly,
and there is no concept of ``partly modified terrain'',
you will probably have to come up with a trick to make terrain modification
be slow.  One way is make the acp (or material?) cost very high.
Another way is to make the alteration happen by removing a material,
such as clearcutting a forest, then letting the action make the
actual change to clear terrain.

@node Vision Parameters
@section Vision Parameters

Vision is an important part of @i{Xconq}.  Information need not come for
free in your game design, and you can design the parameters to control
how much players can get.  The possibilities range from total knowledge
as in board games, where nothing is secret except the enemy's heart, to
games where much of the play hinges on who knows what, and when.

When deciding what visibility model to use, keep in mind that one of the
hallmarks of games in the @i{Xconq} genre is the exploration of the
world during the initial phase of a game.  Not only do many players
enjoy the adventure of exploring a new world, but the progress of
exploration servers as a handy note-taking device for players searching
for other players.  If all the terrain starts out visible, but the
location of the enemy is unknown, it can be difficult to keep track of
what's been examined!

@menu
* Seeing All::
* Coverage::
* Setting the Initial View::
* Vision Range::
@end menu

@node Seeing All
@subsection Seeing All

The simplest thing to do is to set @code{see-all} to @code{true}.  Then
every player sees all the terrain, everybody's units, everybody's
occupants, the whole world and everything in it.  This makes @i{Xconq}
like a conventional video or board game, which is sometimes just what
you want.  Also, since the view matches the world, the game is simpler
for players, who need not concern themselves with possibly out-of-date
information.  Finally, @code{see-all} is more efficient in time and
space, since the general visibility calculations need never be done or
recorded.  Many games include @code{see-all} as one of their variants.

You may also find @code{see-all} to be a useful game debugging aid,
since you can watch what is happening everywhere in the world.  But,
remember that any AIs will most likely adjust their strategy and not
bother with patrolling or guesswork about the enemy, and you won't be
able to debug the other viewing parameters either!

@node Coverage
@subsection Coverage

Still, much of the fun in @i{Xconq} is the potential for surprise.  The
theory of visibility in @i{Xconq} is that each side has a layer of
coverage, which basically just counts the eyeballs looking at each cell.
As your units move around, the coverage in each cell goes up and down.
Any cell with a coverage of zero is not currently being viewed by any of
the side's units.

The unit property @code{see-always} is useful for units like towns,
which are unlikely to disappear secretly.

These two parameters apply recursively, so for instance a city could be
@code{see-always} and @code{see-occupants},
while a building in the city is @code{see-always} and not
@code{see-occupants}, with the net effect that units
inside a city can be seen by everybody,
but not when they enter a building.

@node Setting the Initial View
@subsection Setting the Initial View

The initial view represents the knowledge assumed to have been gathered
over the period of time preceding the game.  By default, players start
out knowing only the immediate vicinity of their initial units and
people.

One way to change this is to set @code{terrain-seen} to true, or
to add it as an available variant for the game; in either case, all
terrain in the world becomes known to all sides.  This is good for
realism, especially for real-world games since about 1900, when
very little of the Earth remained unexplored.  @code{terrain-seen}
can radically change the dynamics of a game; for instance, the
standard game changes from explore-and-conquer to all-out combat.

If making everything visible is too much, @i{Xconq} lets you set a
radius @code{initial-seen-radius} around each initial unit, within which
the unit's side knows everything.  This is useful if your initial units
are somewhat scattered, so as to avoid gaps of unknown terrain in
between.  Also, any people on your side view both their cell and all the
adjacent cells.

Once you've chosen how much terrain is visible, you can control which
units are visible.  The @code{see-always} property mentioned above
affects initial visibility, but in addition there is @code{already-seen}
and @code{already-seen-independent}, which apply to units on sides or on
no side, respectively.  These properties are percentage chances, so you
can randomize how many are known.  For example, in peacetime everybody
typically knows the location of a navy's surface ships, but when the war
starts they scatter to sea and operate more securely, so for those
@code{see-always} should be 0 and @code{already-seen} should be 100.
However, submarines are always more secretive, and perhaps only 1/4
are known to other sides, so an @code{already-seen} of 25 makes sense.
Another example might be monster's lairs, whose positions might be
known by reputation, but if something happens to them, the news does
not get flashed around the world!

@node Vision Range
@subsection Vision Range

The default vision range (@code{vision-range}) is 1, which basically
means that a unit can see into adjacent cells but no further.  You can
set this to higher values, which is useful for tactical- and
person-level games with line-of-sight (LOS) rules.

You can also set the vision range of a unit to 0, which means that it
can only see things in its own cell.  However, as a special case, when
such a unit enters a new cell, @i{Xconq} will show the terrain of each
adjacent cell, but not any units that might be present.  This is so
players can decide which way to move without having to plunge blindly
into unknown terrain or do some sort of awkward ``adjacent cell
examination'' action before moving.  This only provides information
about terrain and units that are seen if the terrain is seen.

@node Designing Backdrop Weather
@section Designing Backdrop Weather

[The four temperature extremes are independent of each other,
so you can make higher latitude temperatures vary drastically with the
season, while equatorial temperatures are much more stable; or vice versa.

Average temperature usually varies more slowly over some kinds of terrain
than others.  For instance, oceanic circulation moderates temperature
swings in terrain that is near open ocean.]

@node Designing Backdrop Economy
@section Designing Backdrop Economy

Economy in @i{Xconq} means pushing materials around.  So if you want an
economy in your game design, you have to define at least one type of
material.  To define the economy, you have to decide where materials
come from, how they get moved around, and how they get used up.

@menu
* Creating Materials::
* Movement of Materials::
* Consuming Materials::
@end menu

@node Creating Materials
@subsection Creating Materials

Materials come into existence by being placed in units or terrain
during setup, by being produced by units or terrain, and by appearing
in newly-created units.

@node Movement of Materials
@subsection Movement of Materials

Once in existence, players can move materials around by explicit action.
You can also define automated material movement that uses supply and demand.
The tables @code{in-length} and @code{out-length} control the distance
over which materials will move each turn.

@node Consuming Materials
@subsection Consuming Materials

Materials exist to be consumed (unless they are relevant to a scorekeeper).
You can set how much each kind of action uses, as well as how much is needed
as a prerequisite, sort of like a catalyst.  You can also set consumption
due to existence alone, plus what happens to a unit when its supply of a
material runs out.

@node Adding Random Events
@section Adding Random Events

What simulation game would be complete without random events?
Random events are handled somewhat similarly to synthesis methods,
in that you set the value of the variable @code{random-events}
to a list of the methods that you want run.
Note that you must still ensure that the probabilities for the
events on your list are nonzero!

Superficially, random events just introduce some unpredictability
into a game.  However, adding it just for its own sake is not
a good idea; in the worst case, the game becomes the infamous
``dice-rolling contest'', where nothing matters except luck.
Random events are more valuable when they introduce risk,
and players have to balance that risk against their goals.
As an example, random losses of cities in the standard game
would be pointless, since players have to have them, and there
would be a chance that all of a player's cities would disappear,
causing the player to lose for no good reason at all.
On the other hand, the chance of losing an expensive capital
ship in shallow coastal waters is enough to motivate the player
to keep them well out to sea.

In the past, bugs or unexpected behavior in random event routines
have resulted in hard-to-reproduce problems.
For the sake of debugging, you should test the game with random
event probabilities set very high, perhaps as a variant so it can
still be played normally.

@menu
* Accident Parameters::
* Attrition Parameters::
* Revolt Parameters::
* Surrender Parameters::
@end menu

@node Accident Parameters
@subsection Accident Parameters

The name of the accident method is @code{accidents-in-terrain}.
Accidents should be restricted to definite hazardous situations, to go along
with movement constraints - for instance, carriers and battleships
in shallow water should have a small chance to hit a rock and sink.

You can specify two kinds of accident; a damaging accident,
which hits the unit as if it were in combat, or a vanishing
accident, in which the unit disapppears instantly.

Damaging accidents occur according to the @code{accident-hit-chance}
table, and damage the unit according to @code{accident-damage}.
The interpretation of these is similar to their combat counterparts.
The @code{accident-vanish-chance} table sets the probability for
the unit to simply vanish without a trace.

@node Attrition Parameters
@subsection Attrition Parameters

Attrition is a sort of higher-probability/lower-damage type
of accident.  It is useful for armies in hostile terrain,
where deserters and casualties slowly reduce its strength.

Attrition can be useful for ``aging''
a unit, if you need to keep the unit from being around too long.

@node Revolt Parameters
@subsection Revolt Parameters

Revolts are spontaneous changes of side, independent of any
other consideration.  Since there is no way to protect against
this, the chance should usually be very small, less than .01;
even a small chance of will cause players to maintain reserves
just in case.

@node Surrender Parameters
@subsection Surrender Parameters

The method's name is @code{units-surrender}; when it runs, it
checks each unit to see if it is within @code{surrender-range}
of a unit on an unfriendly side, and if the @code{surrender-chance}
occurs, then the unit will change to the side of the other unit.
Occupants will also evaluate their surrender/scuttle/escape chances,
and behave accordingly.

@node Designing the Interface
@section Designing the Interface

So far, the game design machinery has been focused on semantics.
The other part of the game design defines how it actually appears
to the players.  This part of the design can be more loosely
designed, which is good, because you cannot guarantee that your
game design will only ever be run with a particular interface,
and there is a wide variety of interfaces.  You could, for instance,
define an elaborate set of color graphical icons and patterns,
only to find that most of your players only have black-and-white
displays.  @i{Xconq} itself will always be able to cope with
your omissions, but it will be forced to synthesize
inferior substitutes.

Game designs have three general categories of interface elements
that they can specify: text, graphics, and animations.
Text elements are just strings describing objects and events
in a readable form, while graphics consist of small icons
and patterns primarily representing units and terrain.
Animations are used to illustrate events as they happen,
and may include sounds.

@node Designing the Text
@section Designing the Text

Although @i{Xconq} is primarily a graphical game system,
it is complex enough that the graphics alone are
insufficient to describe what is going on.

All text that players see is issued by @dfn{text generators},
which are objects that, when given appropriate inputs,
produce text fragments that can be used by the interface
to produce a textual display.
Each text generator has a number of parameters that
may be used to select one of several rules [etc]

@menu
* Describing Objects::
* Describing Events::
* Generating Names::
* Grammar Examples::            
@end menu

@node Describing Objects
@subsection Describing Objects

[fill in]

@node Describing Events
@subsection Describing Events

[fill in]

@node Generating Names
@subsection Generating Names

One of @i{Xconq}'s special features is its extensive machinery for
generating names of things.  You can generate names for sides, units,
and geographical features.  The possibilities range from a simple list
of strings up to context-free grammars and arbitrary code modules.
Naming happens throughout the game, as nameable objects are created, but
is mostly done during initialization.

@node Grammar Examples
@subsection Grammar Examples

Here is a very simple grammar:
@example
(namer (grammar root 40
  (root (or 1 (the animal in the thing)))
  (animal (or cat dog sheep))
  (thing (or hat umbrella fold))
  ))
@end example
It makes phrases like @code{"the cat in the hat"},
@code{"the dog in the umbrella"}, and @code{"the sheep in the hat"}.

This example is more realistic:
@example
;;; German-like place name generator.

;;; Conventional combos most common, random syllables rare.
;;; Needs more conventional words to combine?

(namer german-place-names (grammar root 50
  (root (or 95 (name)
             5 ("Bad " name)
             ))
  (name (or 40 (prefix suffix)
            20 (both suffix)
            20 (prefix both)
             5 (prefix both suffix)
            10 (syll suffix)
            10 (prefix syll suffix)
        ))
  (prefix (or
        schwarz blau grun gelb rot roth braun weiss
        wolf neu alt alten salz hoch uber nieder gross klein
        west ost nord sud
        ;; from real names
        frank dussel chem stras mut
        ))
  (suffix (or
        dorf torf heim holz hof burg stedt haus hausen
        bruck brueck bach tal thal furt
        ;; these aren't so great
        ach ingen nitz
        ))
  (both (or
        feld stadt stein see schwein schloss wasser eisen berg
        ))
  ;; Generate random syllables
  (syll (or 40 (startsyll vowel endsyll) 5 (vowel endsyll)))
  (startsyll (or 30 startcons 10 startdiph))
  (startcons (or b k d f g l m n r 5 s 3 t))
  (startdiph (or bl kl fl gl 5 sl 3 sch 2 schl
                 br dr kr fr gr 2 schr 3 tr 2 th 2 thr))
  (vowel (or 6 a ae 2 au 5 e 2 ei 2 ie 6 i 3 o oe 2 u ue))
  (endsyll (or 4 b 5 l 3 n 4 r 4 t
               bs ls ns rs ts 3 ch 3 ck
               lb lck lch lk lz ln lt lth ltz
               rb rck rch rn rt rth rtz
               ss sz 2 th tz
  	))
  ))
@end example
This generator usually takes normal German words and glues a couple
together, making names like @code{"Schwarzburg"}, @code{"Nordbruck"},
and @code{"Bad Salzwasser"}, but it will occasionally make a completely
random syllable using common German phonemes, then glue it into a name,
resulting in names like @code{"Biefeld"} and @code{"Salzgloelthach"}.
Yes, that last one is unpronounceable even for Germans, but the
generator doesn't know that!

Since there is no special handling to ensure non-garbled names, it
generally does not work particularly well to try to build names from
vowels and consonants.  Either random selection from a list or putting
together syllables seems to do better, with perhaps a single totally
random syllable thrown in.  Don't forget that this is a generator, not a
recognizer or parser, so you don't have to be able to handle every
possible name; just enough to make an interesting variety.

Recursive rules, where a symbol expands into a sequence mentioning that
same symbol, will work, but they are not recommended.  Although the
generator has a builtin limiter to keep from looping forever,
@c and the UGH list is available,  [this is to be changed?]
in general there is no way to avoid getting awful names like
@code{"Feldbruckbruckbruck"}.  Instead, you can just add extra rules,
one for each desired length, so for instance you have a rule for
2-syllable names, one for 3-syllable names, one for 4 syllables, etc.
Another advantage is that you can set the probability of each length of
name separately, and thus lower the probability of longer names, so that
they only appear once in a while and you save the poor players from
being continuously tongue-tangled!

@node Designing the Graphics
@section Designing the Graphics

@i{Xconq} is fundamentally a graphical game; but fortunately, you don't
have to do gnarly graphics hacking to get the pretty pictures!  The
basic graphics handling is built into the interface subroutines of
@i{Xconq}.  What you @i{do} have to do is to choose or design the basic
images.

@i{Xconq} will always attempt to generate some sort of default display
for your new game design, but it's likely to be pretty ugly.  So your
goal here is just to make the display look good.  First off you should
decide about the overall appearance.  Do you want things to be generally
light or dark?  Garish or subtle?  Conventional or exotic?  This is a
good time to cruise the image libraries and to look at the graphics of
other games.  Sometimes the theme decides a lot for you - how could you
display anything other than a red star on a Soviet tank?  You also need
to think about whether you want to concentrate on b/w or color displays,
although again @i{Xconq} will try to do something reasonable for both.

You have to choose three sets of images: terrain patterns or images,
unit icons, and side emblems.  The terrain patterns have to tile
properly, since they may be used to fill in large areas, while both unit
icons and side emblems are single icons.  You can optionally choose
solid colors for terrain, and to ``colorize'' unit icons and side
emblems.

Once you have chosen and specified a set of images, you have to try them
out in various combinations in real games.  What you'll most likely
discover is that they don't always mix like you imagined.  That
cool-looking emblem for a side disappears against the background of
space, or two unit icons are nearly indistinguishable on the map.  At
this point, you have to start making some choices.  Either substitute
some different images, or design new ones of your own.

Color choices are tricky.  Again, the total effect can be quite
different from what you imagined, plus you should be careful about the
variety of displays that your game runs on, or you may be getting
complaints about how your ``olive'' more closely resembles ``puke
gray''!

Here is an example of unit icons:
@example
(add (infantry town city) image-name ("soldiers" "town20" "city20"))
@end example
In general, an icon name should describe the literal appearance of the
image, instead of the type that you want it to represent.  The
@code{"soldiers"} icon, for instance, just shows a row of soldiers; in
one game the icon can be used to represent infantry, in another, armies
in general, and in another, the national guard.  There is an
@code{"infantry"} image also, but it is the standard ``crossed
bandoliers'' symbol, and is really only sensible for specialized
military games.

Here is an example of a terrain pattern:
@example
(terrain-type plains
  (color "green") (image-name "plains") (char "+")
  )
@end example

The @code{"plains"} is defined in @code{terrain.imf}, as basically
a blank 8x8 tile with two pixels turned on, which textures things
somewhat:
@example
(imf "plains" ((8 8 tile)
  (color (pixel-size 1) (row-bytes 1)
   (palette (0 7969 46995 5169) (1 0 25775 4528))
   "00/40/00/00/00/04/00/00")
  (mono "00/40/00/00/00/04/00/00")))
@end example

For extra fine control on color displays,
you can also set the colors of unseen terrain
and the grid separating cells, via the globals @code{grid-color}
and @code{unseen-color}.

Note that some display systems (such as the X Window System)
allow users to customize
most or all of their colors, so individuals may override your choices.
Not much you can do about that though!

@menu
* Image Format::
* Image Design Tools::
* Image Design Hints::
@end menu

@node Image Format
@subsection Image Format

@example
(imf "example" ((8 8) (mono "0011223344556677")))
@end example

[describe when fleshed out]

It may happen that you will want to add an image that is similar to an
existing image.  While you can replace the existing image, you may alter
the appearance of some other game for the worse (perhaps its image
colors have been designed to work together).

The first rule of image naming is to choose the name to describe the
image literally.  For instance, you may have designed an anchor image
that is to represent a port.  However, you should name the image
"anchor" and not "port", so that it may be used in other games.  Second,
if the image should have a difference appearance in different eras or
contexts, you should append that as a qualifier to the basic image name;
so a soldier image from the American Civil War era (1861-1865) would be
"soldier-acw".

Some images are more symbolic than pictorial, such as standard military
symbology.  In those cases the order should be function-size-individual,
so as to get images with names like @code{inf-bn} for an infantry
battalion or @code{armor-div-7th} for an image representing the 7th
Armored Division specifically.

If you want your image to be specific to a particular game, and not
to share with any other games (or be affected by image changes to
accommodate them), prefix your image with the name or abbreviation
for the game.

To summarize, here are the recommended name formats:
@example
[<game>-]<picture>[-<era>]
[<game>-]<function>[-<size>][-<era>][-<side/individual>]
@end example

Finally, if your image has no obvious way to distinguish it, then you
must append a distinguishing number.  So multiple generic dragon images
are "dragon", "dragon-2", "dragon-3", and so forth.

None of these naming rules are enforced by the software; they exist to
bring some semblance of order to a large and complicated image library.

@node Image Design Tools
@subsection Image Design Tools

Whether you use platform-specific paint/draw programs, or
you collect images in other formats, you will need to translate these
into imf format, and then integrate into the existing library.
Typically, each platform includes a tools to help with this;
for instance, the Unix program @code{x2imf} reads X11 bitmap files and
produces imf files, while the Mac program @code{IMFApp} allows both
previewing of images and translation between imf files and Mac resources.

As an additional aid, the program @code{imf2imf} is a Unix program that
transforms a single imf file with many images into a set of files each
with one image, and vice versa.  This is useful when merging sets of images
together:

@example
imf2imf foo.imf --explode -o tmp

<copy other files into tmp dir>

imf2imf tmp/*.imf >newfoo.imf
@end example

@node Image Design Hints
@subsection Image Design Hints

The design of each graphical image can and should be somewhat
independent of the basic game design; this allows for reuse of pictures.

The first thing you should do is to check the image library on your
machine.  The image you're looking for may already be there, but perhaps
under a different name.  Even if you don't find it, you may notice an
image that is close enough to be a good starting point.  The @i{Xconq}
image library presently includes hundreds of images, so the chances are
pretty good that you'll find something useful.

The second thing to do is to look around for images in some other
format, and to massage them into a usable form. 

Designing images from scratch should be your last resort.
Designing good images and patterns is a specialized and demanding
category of artwork that I'm not going to go into here.  My best advice
is to learn from the pros, and don't be afraid to experiment.

@node Game Module Organization
@section Game Module Organization

Each separate file is known as a @dfn{game module} or just @dfn{module}.
A module has a name, displayed name, an advertising-style blurb, a version,
and designer notes.

This is an example of an elaborately-declared game module with no
actual content:
@example
(game-module "foobar"
  (title "Foo of Bar")
  (blurb "An exciting game with lots of cliffhanging suspense")
  (version "1.3")
  (program-version (>= "7.0.3"))
  ;; other properties?
  (complete-game true)
)

;;; contents here

(game-module (notes (
  "This is just a sample game."
  ""
  "It's not really as interesting as the blurb makes out."
  )))

(game-module (design-notes (
  "This is commentary addressed to other designers."
  "Also a good place to mention things to work on."
  )))
@end example
The @code{notes} and @code{design-notes} could have been supplied with
the first @code{game-module} declaration, but in practice, putting the
player and designer notes at the end of the file keeps them out of the
way.  You can supply any number of @code{game-module} declarations in a
file.  Only the first need include a name.

The game module format is only loosely structured.  In general, anything
that you might want to reuse or combine in different ways should be a
separate module.  Good candidates include text generators and maps of
real terrain.  Unfortunately, they don't always mix-and-match as well as
you might like!

The following are the generally preferred module names:

Terrain-only modules should be named @code{t-}@i{xxx}.

Lists of units should be named @code{u-}@i{xxx} or @code{ob-}@i{xxx}
(for ``order of battle'').

Name generators should be name @code{ng-}@i{xxx}.

When supplying a year in the module name, use four digits,
unless the rest of the name makes the
century clear (WWII scenarios are pretty much guaranteed to
be in the 20th century!).

@node Building New Games
@section Building New Games

There are at least three ways to make a new game design: use @i{Xconq}
commands to ``play'' a game and then save it, create and text-edit the
text files defining a game, or write and run special-purpose programs
that create games.  A combination of these techniques will likely prove
the most useful, since each alone has both strengths and weaknesses.
For instance, text editing may seem like a crude approach, but is the
only way to produce certain types of scenarios, and text editors have
many facilities (such as regular expression replacement) not directly
available in @i{Xconq}.  On the other hand, maintenance of the correct
transport/occupant relationships between units is hard to do while
editing text, but comes for free when using @i{Xconq} itself.

@menu
* Building Scenarios::
* Designer Mode::
* Saving Scenarios::
* Preparing a Game for Use::
* Installing a Game::
* Playtesting::
* Safety::
* Balance::
* Complexity::
* Combinations::
@end menu

@node Building Scenarios
@subsection Building Scenarios

The easiest way to customize @i{Xconq} is to build a scenario.  A
scenario is basically a saved game from which irrelevant details, such
as the list of players, has been omitted.  Typically this will include
tweaking details, removing random irrelevant junk, and generally tuning
things.

One way to do this would just be to start a normal game, save it, and
then dig through the saved game and edit it, since the saved game is
itself a game module.  Sometimes this is easy, more likely it will be
quite hard and error-prone.  A better way is available, in the form of
``designer mode''.

@node Designer Mode
@subsection Designer Mode

There are two ways to get into designer mode; one is to start up a game
with the appropriate option (@code{-design} under Unix), which makes
every player with a display a designer, the other is to switch on a flag
after the game has started.  Being a designer is a property of a side,
so in theory a game could have a designer and several other human
players, or even multiple designers (this might be useful in having
assistants to help with the construction of large scenarios, or just to
have displays open to each side's view of the scenario).  AIs
effectively sit out the game while designers are present.

Designer mode enables an additional set of commands on the menu or map
control panel, as well as removing some restrictions on the use of
normal commands.  It also enables more elaborate game saving machinery,
so you can save only the parts of a game that you want to make into a
scenario.

Modifications to normal commands include the permission to look at and
do any command on any unit, including independents and units belonging
to other sides.  For instance, any unit can be renamed at any time by
any designer in the game.  The modications include the following:

@itemize @bullet
@item
Move commands can put any unit at any destination instantly.

@item
Any unit can be put on any side.

@item
Any unit can be disbanded instantly.

@item
Any terrain can changed to any type.
@end itemize

Some interfaces may also provide additional tool palettes and the like.

@node Saving Scenarios
@subsection Saving Scenarios

If you're not in designer mode, then saving the game will save
absolutely everything.  In designer mode, the interface should ask you
what parts of the game you want to save, and what to name the module.

If you don't save everything, then you should start up another game just
to confirm that you got what you wanted, @i{before} shutting down the
@i{Xconq} that you're designing with.  Sometimes you won't have saved
what you thought you did...  It's also a good idea to keep a backup copy
of data, especially the indecipherable area layers; use the nesting
comments @code{ #| |# } around the old stuff, only delete when you're
sure it's no longer of interest.

@node Preparing a Game for Use
@subsection Preparing a Game for Use

Once you've constructed a game, you should bring it to a state where it
can be given to other @i{Xconq} players.  I recommend copying a standard
software release strategy.  This means documenting how to play the game,
documenting how it works internally, removing unused junk and dubious
features, simplifying where possible, resolving open issues if possible,
documenting them as known problems if not.  This gets you to the point
of having an ``alpha'' or ``beta'' version (the terms are not precise!).
These can be given to other people for testing, but should be clearly
identified as test versions, because your testers may pass copies along
to others without you knowing about it.  After some playtesting (see
below), edit your game into its final form, call it 1.0 and release it
to the world!

After you release your game, you may get some feedback about
unanticipated problems.  When you resolve these, and want to make a new
release, be sure to give it a distinct version number.  This will be
important to deciding whether subsequent complaints are about your new
release or some older one.  If you always put the version number into
the @code{version} property of the @code{game-module} form, then it will
be displayed to players when they ask for help on the game.

@node Installing a Game
@subsection Installing a Game

Once the scenario is constructed and saved, you can install it in the
library and otherwise do as you like with it.  See the interface
documents for platform-specific installation details; in general, just
copying the files into the @code{lib} directory will suffice.

@node Playtesting
@subsection Playtesting

Playtesting is extremely important, even for simple game!  You should
try as many combinations of startup options as possible - for instance,
the combo of two humans and one machine might reveal a peculiarity that
is not observed in a two-person game.  You can solve many problems by
adding more restrictions.  Since the scenario is your concept, you are
free to make whatever decisions are necessary to realize that concept;
if somebody complains, they are free to make their own designs.

Playtesting is the time when you may have to sacrifice realism and
favorite theories for playability.  Listen to and watch yourself and
your testers as the game is played.  For instance, you might have
included a city out in the boonies, but in the game it never does
anybody much good, while still requiring some amount of attention
regularly.  Lose it.

Game startup can be confusing to players if they all start out with lots
of units needing to be told what to do.  One solution is to put most
units on automatic behaviors that expire in a turn or two, so that
novices gradually hear from all the units, while experts can still
override right from the outset.  Another approach is to make units
independent and allow them to be captured early on.  Still another
approach is to make units come in as reinforcements at preset times and
locations.  Since players will form their strongest impressions of a
game based on its appearance at startup, attention to this will pay off.

@node Safety
@subsection Safety

While generally safe -- @i{Xconq} shouldn't crash while you are
designing nor upon starting up your scenario -- you can do silly things,
like loading a submarine with battleships as passengers.  @i{Xconq}
won't complain, but it may behave very strangely.  For instance, a unit
might be able to travel with a transport and leave it, but not be able
to get back on again.

One way to test a game is to remove all the scorekeepers and make all
the players be AI-controlled.  The AI code will then act totally
randomly, thus exercising parts of your design that you may not have
thought much about.  A convenient way to try out various scorekeepers is
to put them in variants, then select them upon startup.

@node Balance
@subsection Balance

Game design often involves subtle questions of balance which
will only be revealed by repeated play of the game.

Although as many of the game parameters as possible are checked, there
is plenty of room for subtle loopholes.  You should think carefully
about the consequences of each parameter, being particularly sensitive
to degenerate winning strategies.  Most common are units that are too
powerful, too fast, or are built so quickly that they overwhelm any
opposition.  Players should always be a little ``hungry''; not able to
get quite as many units or as much material as they would really like.

@node Complexity
@subsection Complexity

Although GDL is a powerful language, you should avoid designing a game
that is too complex to be humanly playable.  A single game can literally
define millions of different parameters, each with a range including 100
to 10,000 distinct values.  It is clearly possible to spend many years
exploring just a single set of these!  For more playable and enjoyable
games, either pick a single thing to treat in detail, or else do
everything in a simplified way.  For instance, if you want elaborate
movement and combat rules, avoid or even eliminate materials and
associated material handling rules.

Another thing to keep in mind is that the introduction of a new type may
have far-reaching consequences. For instance, an additional unit type
will need its interactions with @i{all} other unit types defined, as
well as with terrain and materials, and those new interactions may in
turn affect others.  One approach is to introduce a new type as a slight
modification of an existing type, then to share most of the definitions.
Another thing you can do is to put complexity into the variants, so
players with a taste for punishment can indulge themselves, while
leaving the basic game as more of a fun thing.

@node Combinations
@subsection Combinations

Many of the 700-plus game parameters were chosen for their ability to
combine in interesting ways, rather than for obvious usefulness.  For
instance, construction in a city can by default generate an infinite
stream of units.  But suppose you want to put a limit on the numbers of
that type of unit?  One way is to define a material that is essential
for construction of that type, let the builder have an initial supply,
but provide no way to get more of that material.  When it runs out, no
more units!

Another trick is to motivate an activity by making it a prerequisite to
the basic builtin goal of defeating the other player.  The age of
discovery worked this way.  The kings of that time weren't interested in
new lands @i{per se}; they wanted exploitable possessions, that could be
used to get gold, to buy armies big enough to defeat their neighbors.
You could describe this situation almost exactly, by making gold a
material, obtainable only by the discovery and capture of independent
gold mine units, which are thinly scattered over the world and can be
found only by careful exploration.

Be inventive!  Studying the predefined games should suggest many tricks;
the ``Tricks and Techniques'' section below describes even more.  Be
sure to document the trick carefully, or the next time you work on the
game, you might break it, resulting in unhappy players wondering why
their usual strategies don't work anymore.

@node Debugging Designs
@section Debugging Designs

Completely new game designs usually have a number of bugs.  There are
several stages of trouble that you may encounter.  First, the @i{Xconq}
may fail to read a game module completely.  It will try to report what
happened, but if for instance you left out a closing parenthesis, you
may get some strange error messages.  This is just plain old syntax
error trouble.

Once you've successfuly read in your new game, bring up the online help
and scan through to see if the values present are what you thought.
Sometimes the reader does not interpret a module in the way you thought
it would.  The @code{print} form is useful for debugging at this point;
it can show you whether a defined symbol has the value you thought it
did.

However, the most serious problems with games are play balance issues.
Some can be found out by watching a machine player attached to a
display, since its decisions are based on perceived values of the units.
The most subtle bugs can only be uncovered by extensive play
interspersed with judicious alteration of parameters.  I find it useful
to play for a while, then review and adjust the game parameters all at
once, thus avoiding tweaking one parameter only to find that it results
in another being inconsistent.  Parameters interact in many ways - you
should keep this in mind when experimenting.

Something else to keep in mind at this point is that playability should
outweigh realism.  For example, real-life airplanes can travel 1,000
times faster than a person walking on the ground, but airplanes that
could move 1,000 cells in a turn would be ridiculous (try it out,
@i{Xconq} will let you do this!).

@node Tricks and Techniques
@section Tricks and Techniques

This section discusses specific kinds of design problems and ways that
you might solve them in @i{Xconq}.  These are merely suggestions; in the
past, game designers have come up with all sorts of ingenious ideas.  If
you come up with one yourself, please pass it along!

@menu
* Limiting Unit Quantities::
* Handicapping::
* Buying the Initial Setup::
* Leaders::
* Navigable Rivers::
* What Ranges for Values?::
* Fatigue::
* Brainless Units and Scorekeeping::
* Days and Years::
* GDL Optimization::
* Conversion from Xconq 5::
* Xconq 5.x Setproduct::
* Even More::
@end menu

@node Limiting Unit Quantities
@subsection Limiting Unit Quantities

In some cases you may want to constrain the total number of units in play,
perhaps because of performance reasons, or because some type tends to
proliferate more than is desirable, or because your game concept requires
a hard limit on the number of units.  You have several ways to do this.

@i{Xconq} does give you several parameters
that put a simple cap on total numbers, either by unit type or for all
units, and per side or for all sides together.
You can also define a material type that is essential to the creation,
completion, or operation of units, and make that material be hard to come by.
Iron to make ships, gold to pay armies, or food to feed armies could all
work this way.  If the only source of the limiting material is an initial
supply in a starting unit, then this is a hard limit; if production of the
limiting material is slow, then the limit is softer but still very real.

Limits on unit quantities have some interesting uses beyond the obvious ones.
For instance, a
useful type that is limited to at most a single instance could be a sort of
``football'' where the side that has the one unit finds itself being
chased after by all the other sides trying to get it.
You could make a WWII-era game with
``Oppenheimer'' as the only scientist who knows how to make
an atomic bomb (I know, it's not realistic), and have the different sides
trying to kidnap him.

@node Handicapping
@subsection Handicapping

Very rarely will the @i{Xconq} players in a game all be at the same skill
level.  Sometimes this is OK, since weaker players really do learn more
from their losses than their wins.  However, when the goal is to have fun,
or when the difference in abilities is extreme, you can balance things out
in several different ways.

One simple approach is just to design an imbalanced scenario, document
it as such, and let players choose the stronger and weaker sides as desired.
In many cases this should be sufficient; for instance, accurate historical
simulations.

The next most simple solution is to set up sides or side classes and
fill random properties differently.  Weaker players could choose a side with
more technology or whose class allows more powerful units.  This isn't
very adjustable, since all the sides and their property values
have to be predefined.

To enable the most precise match of player abilities, you can use the
@code{initial-advantage} property of player objects.  This property is
a relative value, defaulting to 1, and indicates how strong the initial
unit setup should be relative to the other players.  For instance,
if a three-player game includes advantages of 2/3/7, then the second player
will have three units for each two of the first player while the third
player (the weakest) will have seven.  The implementation of relative
advantages is up to game synthesis, so for example the @code{make-countries}
will adjust all the numbers of initial units to match the requested
advantages.  Note that this affects only the initial setup, and only
certain synthesis methods.
Once a game has started, all sides are always on an equal footing.

@node Buying the Initial Setup
@subsection Buying the Initial Setup

A common form of game setup is to give each player a quantity of
``money'' of some sort, then give them a menu from which to buy things.
The way you would implement this in @i{Xconq} is similar to the method
for limiting unit quantities - make the money be an initial supply of a
special material type not used for any other purpose.  This initial
supply should be given to a first unit that each player starts with.
This first unit could be something like the adventurer in a fantasy game
who starts with a pot of money, so the first unit is also the most
important one, or perhaps a little dummy unit that buys the other units
and then is of little interest thereafter, sort of like the national
bank for the player's country.

Here's an example:
@example
(unit-type adventurer
  (start-with 1)
  )
(unit-type shop
  (start-with 1)
  )

(unit-type sword)
(unit-type armor)
(unit-type boat)

(material-type money)

(table initial-supply (adventurer money 200))

(table acp-to-create (shop (sword armor boat) 1))

(table material-to-create ((sword armor boat) money (20 100 1000)))
@end example
The shop can't do anything besides create items when given money.  The
adventurer starts with the money and has to give it to his/her shop,
then order the shop to create the items desired.  The shop will create
completed items instantly, ready for the adventurer to use.  A slight
simplification would be for the shop to start with the money itself.

Note that this can't be extended to buy extra intrinsic qualities, such
as hit points or action points.

@node Leaders
@subsection Leaders

Some games, particularly wargames set in Napoleonic times or earlier,
feature the concept of a ``leader'' as the sole individual who can make
things happen.  Without a general or field marshal, the army won't move.
Whether or not this is truly realistic, it does have the effect of
focusing the game on key individuals!

One way to do this is to make the leader be a self-unit and limit the
distance of direct control over other unit types.
Another way is give armies 0 acp and allow leaders to push them around,
and still another way is to use leaders as occupants
that add to an army's speed.

@node Navigable Rivers
@subsection Navigable Rivers

The concept of a navigable unbridged river is a real problem for @i{Xconq}.
Non-navigable rivers are easily done as border terrain,
and navigable rivers with lots of bridges can be connections
(since by their nature, connections can never prevent movement).
But a navigable river that can't be crossed easily is more of a problem.
One way is to make a chain of adjacent cells of a water terrain type.
However, this can be quite unrealistic if cells represent large areas,
say 10-100 km across; you can end up with continents consisting of more
river than land.  In some cases, you can define a ``river valley''
terrain type where both vessels and ground units can exist, with the
river border terrain along just one edge of the valley.

You can also allow border sliding.  Border sliding allows a ship to pass
along the length of a border, but it does require the ship to be in
compatible terrain at both ends of the border.  So define the river
as a chain of alternating water cells and water borders connecting them
together.  Then the river acts as a barrier to units wanting to cross,
while allowing them to see over to the other side,
and at the same time ships can pass up and down the river freely
(modulo any ZOC exerted by units on either side).

@node What Ranges for Values?
@subsection What Ranges for Values?

One of the problems that you encounter when defining a lot of interrelated
units with lots of properties and tables
is to decide where to start out with the numbers.
There are a couple ways to get started.

First, you can start from real-world numbers.  Let's say your game concept
is based on turns that last about one day, and you want to use worlds
with cells that are about 10 miles across.  Now a person in good shape
can walk about 2 miles per hour, or 20 miles in a day, which comes out
to 2 cells/turn as @code{acp-per-turn} for units on foot.  This allows
a speed of 1 cell/turn for injured, tired, or overburdened persons, via
the various speed modifiers.  However, if this same game includes
automobiles and airplanes, then using the same calculation,
we get automobiles that can move 60 cells/turn and airplanes that can
move 600 cells/turn!  The massive disparity in speeds makes for poor
playing; every turn each airplane will make 300 moves while the foot
traveller makes 1.  To make the game work, you'd have to make airplanes
slower (they have to refuel a lot perhaps) or make people faster (nobody
walks anywhere anymore).  So the real-world numbers approach isn't
foolproof.

Another way to go is to start with the smallest values and work up.
For instance, in the monster game above, you could assume that the mob moves
the slowest, and give it a speed of 1.  Then you say that the national
guard should be able to move twice as fast, and give it a speed of 2.
Then the monster should be able to chase and catch mobs and guards
that run away, so you give it a speed of 3 or more.  This approach
is more painstaking, particularly when lots of numbers are involved.

You can use both approaches together as well, working with real-world
numbers until they get too weird, then adjust to make relative values
sensible, then do some more real-world calculations.
As always, only playtesting is the final arbiter.
Once the numbers ``feel'' right in a game,
only the obsessive-compulsives will care about their exact values.

@node Fatigue
@subsection Fatigue

Players are often unmerciful to their units, moving them nonstop,
going into battle after battle, never a thought for how tired the
poor units might be.
Although @i{Xconq} does not include fatigue as a basic concept, it does
have several ways to implement the effects of fatigue.

One way is to use acp debt.  If you allow the acp to go negative during a turn,
then the player can work the unit really hard for one turn, then it has to
rest until its acp builds up to positive levels again.  While acp is negative,
the unit can take no action on its own.  Over a period of
time, the effect is that of a unit that can only do so much,
but can exert itself when needed.

Another way to do fatigue is via a material type, perhaps called
``energy'' or ``enthusiasm''.  As an abstract sort of material,
don't let energy be passed around (unless you want to have ``infectious
enthusiasm'', might be useful sometimes for leaders and morale builders).
Units need energy in order to move, and can consume energy faster
than they produce.  For instance, if a unit has a speed of 3 hexes/turn,
consumes 2 units of energy per move, and only produces 4 units of energy
each turn, then on the average the unit will only be able to move 2 hexes
in each turn, although if it saves up energy, then it can move the full
3 hexes.
Since different kinds of terrain can have differing productivity,
you can also make some kinds of terrain be more tiring than others.
A resort hotel unit could also be allowed to transfer energy to its
residents, restoring them faster than a Motel 6.

@node Brainless Units and Scorekeeping
@subsection Brainless Units and Scorekeeping

One special case to watch out for occurs in games with ``unintelligent''
units, that is, they have an acp of 0.  If a side loses all of its units
except for the unintelligent ones, the player will not be able to do
anything except wait for the game to end.
This might be OK, for instance if the idea of the game allows
for a side to own a particular unit, whether or not it can do anything
with it (perhaps the unit is a fort, and a side can win if it owns the
fort, even at the cost of all its other units).  Usually, however, the
side ought to just lose, in which case you will need to define a special
scorekeeper that requires each side to have at least one of some
sort of unit with acp > 0, or else it loses.

@node Days and Years
@subsection Days and Years

[should go elsewhere]

The @i{Xconq} world can be made to revolve around its sun and to rotate
on its axis. [etc]

To get a realistic hour-by-hour simulation, say
@example
(world
  (day-length 24)
  (year-length 8766) ; this is 365.25 days
  )
@end example

@node GDL Optimization
@subsection GDL Optimization

The @code{add} form is very powerful and very useful for making
groups of objects share some data.  The grouping also helps the
designer to see how sets of numbers compare to each other.
In other words, instead of having multiple forms:
@example
(unit-type foo
  ...
  (acp-per-turn 3)
  ...)
(unit-type bar
  ...
  (acp-per-turn 49)
  ...)
(unit-type baz
  ...
  (acp-per-turn 2)
  ...)
@end example
you can say
@example
(add (foo bar baz) acp-per-turn (3 49 2))
@end example
to get the same effect.

To get an inheritance-like effect, you can append lists of types
together, as in
@example
(define mammal (dog cat cow))
(define bird (hawk eagle condor))
(define animal (append mammal bird fishie))
@end example
which results in a list of seven types.  It is possible to append
different kinds of objects together.

@node Conversion from Xconq 5
@subsection Conversion from Xconq 5

There are many scenarios extant from the version 5 of @i{Xconq}.
Many of them are good games despite some of the quirks of version 5
that they had to work around.
Converting these scenarios to the new GDL syntax should provide some great
new modules and at any rate provide a goldmine of ideas for updated @i{Xconq}
game modules.

A set of conversion scripts are provided that will help to ease the
transition from version 5 to version 7, but they won't save you from
learning the new GDL syntax or features.
These scripts will NOT generate working games modules, but they will
generate valid GDL syntax, and thereby spare you much tedium in conversion.

The first thing to consider is the naming of the files/modules.
There are already some loose guidelines for naming version 7 game
modules (@pxref{Game Module Organization}).
Terrain or worlds should be in modules named @code{t-xxx.g}.
These are roughly equivalent to version 5 @code{.map} files.  Collections
of units, such as the cities to populate world maps, should be in
files named @code{u-xxx.g}, where @code{xxx} generally identifies which
map they go with in addition to a general identifier (e.g. @code{1942}).
Name generators are in files of the form @code{ng-xxx.g}, but you probably
don't know or care about these yet.  And finally, if you are building
a set of scenarios based on a core set of rules, you should consider a
naming scheme that will link them all together so that players can
find them easily.

Having said all that, let's get on to the conversion.  The conversion
scripts go somewhat blindly on the assumption that you've split
everything up in the ``standard'' way.  That is, assuming that you've
got a spiffy big scenario, that it comes in three parts: a
period definition, a map and a scenario file.  If not, if you've
@emph{dared} to combine some of these files, you should split them
manually before starting the automated part of the conversion.

Convert the map using @code{map2g}.  You want to use the -o option and your
new t-something name and the -b with a full pathname to the period
file that has the terrain type definitions in it.  This allows @code{map2g}
to set the default base module and the get the appropriate character
list for creating the map file.  The generated world will have its
circumference set to match the width of the generated area,
i.e. it will wrap from side to side.
This is because all maps are cylindrical in version 5.

Next, do a pass over the @code{.scn} file with @code{scn2g}.
Again you should use -o to get the naming the way you want it.
This should leave you with
a very pretty set of units and a very rough hack at a set of victory
conditions (i.e. scorekeepers).  The scorekeepers will need to be
completely reworked, since they work rather differently in version 7.

Now the home stretch, convert the @code{.per} file with @code{per2g}.
Keep an eye on the output.
If it complains about ``unknown keywords'' then you've
probably used one of the more obscure features of version 5.  Don't
panic because your obscurity will be preserved--commented out--in the
resulting game module.
Now you have to edit the module and start sorting out the
bits that @code{per2g} couldn't handle.  Search for occurances of FIX.
These are lines inserted by @code{per2g} to note places that need
your attention.
@code{per2g} may have done nothing to the line except comment it out,
or it may have done a partial (or partially correct) conversion,
or it may have done a complete and valid conversion but wishes to call your
attention to related forms that can be added.

For this process you are going to need to have the documentation
close at hand to make sure you get the syntax right.  The best thing
to do is read thru this chapter of the manual and then have
the Reference Manual chapter on hand while editing the module.

Generally the place to start will be the @code{make} and @code{maker}
lines from the old period definition.
These are not converted at all by @code{per2g}
(because the machinery has changed so radically in version 7),
but are often essential to being able to start up a game.  From there you
can work your way through the rest of the file with frequent references
to the manual and occasional test runs.  Check out the debugging tips
in this chapter.

@node Xconq 5.x Setproduct
@subsection Xconq 5.x Setproduct

@i{Xconq} version 5 had a sometimes-useful flag called ``setproduct''
that could be set to false, with the effect that any attempts to
@i{change} construction were disabled.  So for instance, a city that
was set by a scenario to build bombers would then build bombers
throughout the game.  The advantages were both in realism (retooling
a factory can be very time-consuming) and in playability (no construction
planning required).

To emulate this in version 7, you can set @code{acp-to-toolup}
to be zero for cities, but at the same time require 1 tp for each
type that the city can construct.  In the scenario, set the value
of the city's tooling to be 1 for the one or more types that you
want it to specialize in (maybe switching between fighters and
bombers should be possible, but not to submarines).
Players can then start and stop construction as desired,
but are limited to only particular types.
Even captured independent cities can be limited in what they
can be used to construct.

@node Even More
@subsection Even More

An unwanted unit in a shared library file
could be gotten rid of by matching on id or
name and then setting hp to 0;
@code{(unit "Corinth" (hp 0))}, for instance, would eliminate
Corinth from an ancient Greek game.

Elevation data, while interesting to include, can take up a lot of space
and be more detailed than necessary.  The parameters here allow you to
restrict elevations to a smaller range of values, which will allow
for more compact encoding and simpler games.
For instance, a game set in rolling countryside doesn't need a huge
range of elevations; you could set elevations to range from 0 to 300
meters, in 30-meter increments.  Then only 4 bits will be needed to
encode each value, and yet the player will still see reasonable values
like "150 meters", and formulas for temperature and other elevation
dependent data will be correct.

Note that just because a player controls a side doesn't mean that the
controlled side can be taken out of the game; for one thing, certain
types of units will not change sides under any circumstances.

People materials should usually not be directly movable
between units.

ZOC should be less than combat range usually,
since it means that exerter should be able to
control ground (but could attack further in multiple turns).
ZOC levels should be only those reachable by the unit.

With all the costs of moving around,
it may be that a unit has movement points left, but
not enough to meet the full cost of a desired move action.
You can allow player extra movement points to complete the action
by setting @code{free-mp} to effectively add the needed mp.

@c [to refman?]
A hit on a complete unit should reduce by whole cp/hp, otherwise
it will appear to be incomplete.  @i{Xconq} will not fix this,
you have to arrange all the numbers yourself, or run the risk
of player confusion.

Bases should "anti-protect" aircraft in games involving both, but
fighters should protect the base.

@node Designing with the Common Interface
@section Designing with the Common Interface

The common interface includes both the Unix/X11 and Windows versions;
game design works the same for both.

The common interface provides a @dfn{design mode} that allows you to
do many game design tasks interactively.  At present, you can use it
to lay out maps, specify the contents of the different area layers,
and set up units.  You can then save chosen elements of the design
into a file.

@menu
* Common Interface Design Mode::
* Common Interface Design Palette::
* Common Interface Design Save::
* Common Interface Image Families::
@end menu

@node Common Interface Design Mode
@subsection Common Interface Design Mode

There are several ways to get into design mode; you can specify
@samp{-design} on the command line, you can choose Design from the Edit
menu, or you can type in the long command @samp{design}.  When you do
any of these, several things will happen: the side list will mark your
side as a designer, the Show All item in the View menu will appear, and
you will get a popup window with a palette of designer's tools.  The
popup applies to all maps equally.

The identification in the side list is for the benefit of other players,
since it is actually possible to enable designing in a multi-player game.
@c but maybe should disable, or else enable for all players
@c simultaneously??  Somebody could enable designing, hack a bit,
@c then switch back before anybody else in the game noticed...

The Show All view control allows you to see everything accurately.
It is switchable so you can compare what things look like to the player
vs what they are in reality.  This is also important for side view
painting, which is useful for exploration-based scenarios.

Note that the online design mode is powerful, with few restrictions.
This means you can scramble things if you're not careful.  Frequent
saves are a good idea.

@node Common Interface Design Palette
@subsection Common Interface Design Palette

The design palette consists of a number of buttons next to a varying
frame whose contents vary depending on the button pressed.  Each button
corresponds to a different sort of painting/placement mode.

@table @code

@item Normal
This mode corresponds to normal survey mode.  This mode is mainly for
moving units around.  You can move a unit by left-clicking to select it,
then right-clicking on the desired destination.  You can even
right-click on another unit to have the selected unit become an
occupant.

@item Paint Terrain
In this mode, clicking and dragging in any map paints terrain, just as
if you were using a standard paint program.  The varying frame displays
samples of the terrain, as well as two popups, one for @dfn{foreground}
terrain and one for @dfn{background} terrain.  The foreground type is
what normally gets painted.  However, if you click on a cell of the
foreground type, you will paint the background type into the cell, and
will continue to do so when you drag the mouse.  This makes it easy to
toggle when you're fine-tuning a coastline and so forth.  (It's easier
to use than to describe!)

You can also select border and connection types to paint, in which case
clicking toggles the existence of the border or connection.  The
background terrain type is not used while painting borders and
connections.

Note that you don't need to follow terrain/terrain or unit/terrain
compatibility rules while painting; you can paint sea underneath a city
if you like, or rivers through icefields.  However, the city will
quietly disappear from the game when you start up the modified module.

@item Place Unit
In this mode, clicking on a map creates and places a unit.  Popups in
the varying frame let you specify type and side.

As with terrain painting, compatibility rules are not enforced.

@item Paint People
This mode lets you specify the side of the people in each cell.  The
varying frame's popup lets you choose the side, then clicking/dragging
paints.  Clicking on a cell with people on a different side converts
them to your selected side, while if the people are on your selected
side, then the cell becomes empty (not independent!).

@item Paint Control
This mode is very similar to the people-painting mode, but applies to
the control layer instead.

@item Paint Feature
This mode is for painting geographical features.  You choose the
feature from a popup menu.  You can also create new features and
edit the name of any feature.

You should turn on the display of display feature boundaries.  The
feature you're painting have its boundaries drawn red, while the
other boundaries will be gray.

@item Paint Material
[not yet implemented]

@item Paint Elevation
Use this mode to set terrain elevations.

@item Paint Temperature
Use this mode to set temperatures.

@item Paint Clouds
Use this mode to set cloud cover.

@item Paint Winds
Use this mode to set winds.

@item Paint View
Use this mode to paint the side view.  At present, this only works on
the designing side's view.  In his mode, the paintbrush toggles the
view between unknown and an accurate view of the terrain and units
in each cell.  Turn off the Show All option on the View menu to see
the effect of this; unknown terrain will still be visible, but dimmed.
You need to switch out of designer mode to see exactly what it will
look like to a game player.

@end table

Below the buttons is a popup with a numeric label.  This sets the radius
of the paint brush.  A radius 0 brush affects only a single cell, while
radius 1 applies to the cell and all adjacent, and so forth.  The radius
goes up to 9, which is spectacularly large for most maps, and always at
risk of painting over something you wanted.  A brush size of 2-3 is more
useful for roughing-in shapes.  There is currently no undo for painting,
so be careful!

@c the following would be nice to have, but they're not implemented anymore
@c @subsection Shortcuts for X11 Xconq Designers

@c @itemize @bullet

@c @item
@c Clicking on the ``sides'' subwindow will select the current side.

@c @item
@c Clicking on the ``unit types'' subwindow will select the current unit
@c type.

@c @item
@c Clicking a cell with the right mouse button in terrain-drawing mode
@c will select the current terrain.

@c @item
@c Clicking a unit with the right mouse button in unit-adding mode will
@c select the current unit type.

@c @item
@c Clicking a unit with the right mouse button in people-drawing mode
@c will select the current side.

@c @item
@c Clicking a cell with the right mouse button in feature-drawing mode
@c will select the current feature.

@c @end itemize

@node Common Interface Design Save
@subsection Common Interface Design Save

If you go to save the game while designing, you will get a much more
elaborate dialog than for normal saving.  Use the checkboxes to decide
which elements of the design to save.

@node Common Interface Image Families
@subsection Common Interface Image Families

@i{X11 Xconq} can use images in either its portable image family format,
or as bitmaps.  However, since images in portable format will work with
other interfaces, you should only use bitmaps while prototyping,
and translate them into portable form using @samp{x2imf}.

To translate image families into bitmaps, use the tool @samp{imf2x}.

The program @samp{xshowimf} displays image families.

Control the display of three-color images (mono+mask) with the resource
@samp{maskColor} (see @samp{XShowimf-co.ad} or with the command-line
argument @samp{-mc}.

To edit the image families, do something like
@example
mkdir tmp
xshowimf [imf/xbm/xpm files...] -o tmpdir &
(cd tmpdir; xpaint) &
@end example

@node Designing with the Mac Interface
@section Designing with the Mac Interface

Designer's tools and capabilities are available via the Design item in
the Edit menu, or by typing @samp{design} into the Command window.  The
display changes to show you everything in the world, you get a number of
special privileges (such as the ability to look at and move ANY unit),
and you get a designer's tools palette.

@menu
* Using the Palette::
* Mac Interface Images::
* IMFApp::
* Mac Interface Sounds::
@end menu

@node Using the Palette
@subsection Using the Palette

In general, palette items use Option-click and Option-Shift-click to
cycle through possible values, and many also have a popup menu.  Also
note that the selection can be changed without changing the tool; you
have to click in the tool and get a heavy border around it before the
tool is actually changed.  Each type of designer tool has a distinct
cursor when over a map window, so look for that as well.

@table @code

@item Normal
In this mode the mouse behaves just as in normal survey mode.

@item Painting Terrain
If you select the terrain item in the palette, then clicking/dragging in
a map paints the current terrain type displayed in the palette
(Option-clicking the terrain item cycles through all the types,
Shift-Option-click does the same thing in reverse order).  The
background terrain type can be cycled via Command-click and
Command-Shift-click.

@item Creating Units
The unit item includes a popup of all unit types.  Use it to select the
unit type you want to create, then clicking on a map window will place
the unit at that location.  Unit placement ignores stacking limits,
terrain compatibility, and other issues, so you may be able to place a
unit but not have it successfully appear there when a player tries to
use the game module.

The side item includes a popup with all the sides listed, including the
``independent'' side.  Use it to set the side with which a new unit will
be created.  Not all units are allowed on all sides - @i{Xconq} marks
the sides that are allowed with the current unit type, and the unit
types that are allowed with the current side.

@item Painting People
If you select the side item in the palette, you can click/drag in a map
to set the side of the people in the cells clicked or dragged over.

Note that the chosen side affect either people painting or unit
creation, depending on which item is selected as the painting tool.

@c @item Painting Material
@c You can create materials in the terrain by selecting the materials
@c item in the palette, then painting in any map.

@item Creating Named Features
The features item in the palette includes several buttons and a popup
menu that displays all the features currently defined.  You can click on
the buttons to create, destroy, and rename a feature.  You can add or
remove cells of a feature by painting in any map.

@item Setting Brush Size
The Brush item sets the area of effect of the painting tools.  A brush
radius of 0 (the default) results in painting affecting only the cell
in which the mouse is clicked or dragged, while a radius of 1 causes
the adjacent cells to be affected also.  Adjust the brush size up and
down by option-clicking and option-shift-clicking in the brush item.

@item Painting Elevations
You can set the elevations of terrain by selecting the elevations item
in the palette, then painting in any map.

@item Painting Views
When you select this item, you get a tool that toggles the designing
side's view of a cell.  The toggle goes between unknown terrain and
an accurate view of the cell and any units in it.

@c @item Painting Temperatures
@c You can set the temperatures by selecting the temperatures item in the
@c palette, then painting in any map.

@c @item Painting Winds
@c You can set the direction and force of winds by painting them.  The
@c values of direction and force are controlled by Option-click
@c (Option-Shift-click for reverse direction), and Command-click
@c (Command-Shift-click for reverse direction), respectively.

@c @item Painting Clouds
@c If you select the clouds item of the palette, you can set the density of
@c cloud cover by painting.

@end table

@node Mac Interface Images
@subsection Mac Interface Images

If you want to change the icons and pictures in an existing game,
or if you want to define new ones, you can do this either with a
resource editor such as ResEdit, or with a resource compiler such as Rez,
or by editing the portable ``imf'' files.  @i{Xconq} can use PICTs, icons,
and patterns to draw with; collectively these will be called ``images''.
A group of images that all represent different views of the same thing
is an ``image family''.  The concept is similar to the icon families used
by Macintosh programs, but is much more general, since you can have any
number of images of different sizes and depths, as well as images embedded
in each other.

@subsubsection Icons and Patterns

The resource file @code{:lib-mac:Images} is the main repository of Mac imagery.
You can resource-edit this file, close it, start up @i{Xconq}, and see
the results.  For instance, if you want to improve the appearance of the
``city20'' image, you will find a 32x32 @code{'cicn'} with that name as
well as a 16x16 'sicn'.  You can modify these as you like.
Note that the 'sicn' includes a mask sicn, as does the @code{'cicn'}.
Masks are optional, but improve the appearance of the images.
If you have a new type in a game and you want an image for it,
just create a resource, such as a @code{'cicn'}, give it the name of
the type or its @code{image-name} property, and you're done.

The standard resource types for images are @code{'cicn'}, @code{'ICON'},
@code{'PAT '}, @code{'ppat'}, @code{'SICN'}, and @code{'PICT'}.
If a resource of one of these types has a name
matching the @code{image-name} (or the type name if no image name is defined)
of a type in a game, then @i{Xconq} will use that resource.
There are two additional resource types: @code{'XCic'} and @code{'XCif'}.
The @code{'XCic'} resources are named colors that can be referred to via
@code{color} properties of types and sides.
@code{'XCif'} resources are raw image family forms
in GDL syntax.  If the contents of an image family can be totally defined
by the standard resource types,
then there need not be an @code{'XCif'} resource,
but if an image has any embedded subimages, or a specific location for
subimages, then this information will be in the @code{'XCif'} resource.
You can edit by defining this resource type as @code{'TEXT'},
which will give you a text editor for the resource, or by just
opening the @code{'TEXT'} editor on the resource.
For more details about the syntax of image families in GDL,
see the reference manual.

Warning: don't ever make a @code{'cicn'} with id 256!
For some reason, if there is a @code{'cicn'} 256 in either the application
or in any of the resource files that it has open,
the small color icons in both the apple menu (far left)
and the application menu (far right) become small unrecognizable blobs.
This effect seems to be innocuous behaviorwise, but the appearance is poor,
and users choose menu items by looking at those icons, so trashing them
is a bad thing to do.

@subsubsection Game Preview Pictures

If the Resources file has a PICT whose name is ``<game-name> game'',
then if a player selects <game-name> in the new game dialog, this PICT
will be displayed in the dialog.  This is useful to give prospective
players more of an idea of what the game might be like,
plus it's a chance to show off your artistry!
(If you're a lousy artist, just make a screen shot of the map and use that.)
The area for the picture is about 200 pixels across and 100 high;
pictures smaller than that will be centered, while larger
pictures will be clipped to fit.

@node IMFApp
@subsection IMFApp

IMFApp is a utility for examining and converting the image families
used by Xconq.

The general concept of image families is similar to that of the Finder icon
families, where several depths and sizes of an icon are available for
use in different situations.  Xconq adds extra complexity to the
concept by including tiling patterns, by allowing icons to be embedded
in each other, and by using the same image families on several different
platforms.

The platform-independent format would
be hard to edit, so IMFApp includes functions to convert between the
common format and Mac resources.
These functions are available from the File Menu.

In addition, IMFApp also allows you to look at the images.
You can control the images' size, overlay, and use of color.
The primary use for this is to test how an image works in various
situations.  Also, if you design games, this is a good place to
start when choosing images for your game.
Since there are hundreds of images available already,
the chances are good that the images you want have already been designed.

The File menu has items to open and save imf and resource files.
New clears any existing images.
Opening multiple files merges their contents.

The Edit menu is not used.

The View menu includes all image appearance controls.
Everything in this menu affects only the @emph{display} of the images,
and does not, in any way, affect the image families themselves.
Display options include size of images, color/mono, name, mask,
background/emblem images, and more.

@node Mac Interface Sounds
@subsection Mac Interface Sounds

Mac @i{Xconq} handles sounds in a very simple way.  The resource
file @samp{:lib-mac:Sounds} includes a number of named @code{'snd '}
resources.  If an event movie includes a form like @code{(sound "pop")},
then the event occurs, Mac @i{Xconq} will look for a sound resource
named @code{pop} and play it.
