throne
A game scripting language for rapid prototyping and story logic:
// declare initial state as 'phrases', one phrase per line
happy
money 70
// define rules of the format: INPUT = OUTPUT
happy . money X . > X 50 . - X 50 Y = sad . money Y
// final state will be:
// sad
// money 20
Rules are of the format INPUT = OUTPUT
, where INPUT
and OUTPUT
are lists that use period (.
) as a separator between items:
INPUT
is a list of one or more conditions that must pass for the rule to be executed. The conditions can either be state phrases that must exist or predicates (such as>
) that must evaluate to true. Any matching state phrases are consumed by the rule on execution.OUTPUT
is a list of state phrases that will be generated by the rule if it is executed.- Identifiers that use capital letters (
X
andY
in the snippet above) are variables that will be assigned when the rule is executed.
Evaluating a throne script involves executing any rule that matches the current state until the set of matching rules is exhausted. Rules are executed in a random order and may be executed more than once.
Examples
- blocks: a simple tile matching game
- Used in Urban Gift
Design
Strongly influenced by https://www.cs.cmu.edu/~cmartens/ceptre.pdf.