Sauerbraten RPG

Running

To launch the game, run the "rpg.bat" file which is included in the main Sauerbraten install directory.

Building

A Visual Studio solution and a Code::Blocks project file are included for building in the "src\rpggame\" directory within the Sauerbraten install directory.

Gameplay Scripting

The RPG is set up in a very open way such that all gameplay objects and behaviour can be modified in a script file, currently in data/game_rpg.cfg (this will change later to be on a per-map basis). The idea is that every map comes with its own "mod", and that gameplay can be influenced by level designer, allowing gameplay types spanning from a stat/story influenced FPS game, an action RPG, all the way to more complex quest/story/stat based RPGs.

This file simply lists all gameplay objects, which can then be placed in the level editor. For example, by writing:

spawn_apple = [ r_worth 20 ]

you define a script that gets executed when an apple is spawned. You place this apple either directly in the world or as part of another objects inventory. To place it in the world, you create an entity of type "spawn" with a name attached. This is best done by typing (in the console):

newrpgspawn apple

which will show you your new entity in the editor. Running the map then will create a new apple object at that location, with all stats set to your liking (in this case just its worth).

What is important to realize is that most r_ commands work with what is called the RPG stack. This makes it possible to apply properties and actions to things without having to specify all the time which object you are talking about. For example, when the spawn_apple script gets executed, the apple object will be on the top of the RPG stack, so any commands such as r_worth that apply to an object, will automatically apply to it. It is a stack, because during the initialization of one object you may spawn another, which means all r_ commands will apply to the new object, until it is done, when the RPG stack returns to the previous object.

Following is a list of all commands... unless otherwise noted, they apply to the current object (top of the RPG stack).

RPG object commands

r_pop

Removes the top object from the RPG stack

r_spawn N

creates a new object, places it on the top of the RPG stack, then executes spawn_N to initialize it.

r_contain T

Takes the object on the top of the stack, and makes it part of the inventory of the object on the stack below it. T is the type of inventory object, see the convenient scripts r_inventory, r_loot, r_fortrade instead.

r_model M

Specify model M to represent this object visually when placed in the world

r_action N A

r_quest N A

defines a custom action the player can take on this object. N is the tag word that describes the action, visible in the objects menu in the game world, and A is the script that gets executed when the player selects it.

When A gets executed, the top of the stack will be object on which the action is defined, below that target of the action, and below that the user of the action. For example, the player (user) casts a fireball (object) onto a monster (target). Or, the player (user/target) interacts with an npc (object).

A special tag is "use", this is the default action for items to be executed when the user clicks on them in the inventory, or, it is the action that gets executed when the player casts the currently selected spell (also see usetype below).

r_quest is the same as r_action, except that it also marks the start of a quest, with the action being the resolution of the quest. The quest description is whatever the last r_say command was. Any r_take inside the action with a positive outcome concludes the quest. Quests can be seen in the quest log.

r_say T

Make text T the last thing this object said to the player

r_take N A NA

Attempt to take object with name N from the player inventory, and place it in the objects inventory. If the item was succesfully grabbed (it was present), action A is executed. If the item was not available, NA is executed. r_take is the preferred way to structure resolution of quests, i.e. everything the player ever needs to do should go via token items.

r_give N

give the player an item with name N

r_applydamage D

does D damage to the object on top of the stack. object one below the top of the stack must be the one doing the damage.

r_use

select or use the object for the player (see usetype below).

RPG stats & attributes

The following is a list of all stats tracked by each object. A stat is defined as a property of an object that determines its effectiveness when performing a certain action, i.e. the "melee" stat affects your melee combat effectiveness. Stats are things that you can build up thruout the game, hence "health" is not a stat, but it is dependent on a stat, maxhp.

a stat can be set on any rpg object using the r_X command, where X is any of the above stat names, e.g. r_melee 50 gives the current object 50 melee points. a script can read the current points using r_get_X, i.e. echo "your melee points are: " (r_get_melee) outputs the current objects melee points.

A special case are objects that have no stats set directly (typically the player, and sometimes NPCs): their stats are computed as cumulative from the stats of all their inventory items. So if the player carries a gem that has melee 50, and gloves that have melee 20, his own melee points are 70.

It's important to realize that stat points do not directly translate to damage and such. Points are an indication of efficiency of a particular stat over the base 100%, along a logarithmic curve. So 0 melee points translates into 100% melee efficiency, and what 70 melee points translates into... well, something above 100%, depending on the log curve. Every map can define their own log curve for each stat, depending on how fast you want points to result in increased melee damage. This is a game balancing thing, in the sense that if the game world makes obtain items with melee points too easy and the log curve is too gentle, then players will be overpowered. The formula for melee is (other stats work similarly):

meleedamage = weapondamage * ( log ( points / pointsscale + 1 ) * percentscale + 100 ) / 100

(log = natural logarithm). so with a pointscale of 10, and a percentscale of 25, our 70 points amount to a 152% melee efficiency, which, when combined with a weapon that does 10 damage (at 100%), now does 15 melee damage. For movespeed you'd have a similar formula, where instead of weapondamage you'd have the default running speed.

You can get the efficiency of any stat using r_eff_X, e.g. r_eff_melee.

That may seem like a really convoluted way of doing things, but the log scale is the only way to give a relatively constant challenge level in the game. Without it, the game would start hard and become too easy real soon. The UI will show both points and efficiency for stats so you can easy see the effect without understanding the math.

You can define the log scale by doing: r_def_X pointscale percentscale, but this should only really ever be done by the game designer, or experienced rpg level designers on their own levels, as tweaking these values requires deep insight into how players will collect points thruout a game.

It is worth repeating what should be obvious from the above: the player and npcs don't have "levels" as in other RPGs. Increased ability is purely denoted by means of points and efficiency above whatever is the 100% value of the related ability. The end result is similar to traditional RPGs, but not quite. The above system is more flexible in the sense that you can have completely independent "levels" for all your abilities. But best of all, since your points are determined by what you have in your inventory, any way you can get items can increase your ability, which includes killing, stealing, finding, trading etc. You can change how you assign your priorities mid-game, by trading melee items for magic items, for example. You won't hit a "item plateau" as in so many RPG games 20% into the game because most items you get are useless, here you can put everything to some use, even if sometimes minimal.

The following are the attributes of any rpg object. Attrs are simpler in the sense that they are just variables kept track of per object, and can be set/changed by either the rpg system or the script code. They are all default 0 for a newly initialized object.

These can be used similarly using r_X and r_get_X.