one dataset · paper, tables, graph, wiki
simgrammar the grammar of simulation

parts

6 mechanics, as Versu does them

core · 2

social relations

Social exchanges

Social practices such as a dinner party or a conversation offer role-specific actions with preconditions, and most actions change how characters regard each other.

agents & behavior

Utility action selection

Agents score each available action by executing it on the world state, evaluating the result against their desires, and undoing it; the best-scoring action is taken.

supporting · 4

agents & behavior

Memories and thoughts

Fine-grained emotions on Ekman's typology record their target and cause.

agents & behavior

Personality traits

Each agent chooses its next action from its own beliefs and desires, which weight its action scoring.

social relations

Relationship values

Agents hold evaluations of each other on roles such as attractiveness or breeding, which actions raise or lower.

narrative & generation

Storyteller director

A drama manager agent can act to push an episode's authored plot.

core loop

choose a character and episode -> practices offer actions for the situation -> player acts or waits -> other agents simulate each option and take the best for their desires -> emotions, evaluations, and relationships update -> the episode reaches an outcome

design notes

Richard Evans and Emily Short built Versu around social practices: recurring situations such as a meal or a conversation written as reactive joint plans that offer actions to participants without controlling them. Each agent tests a candidate action by applying it to the world state, scoring the result against its desires (over 300 in total), and undoing it, which the authors contrast with the estimated consequences used in The Sims. World state is a set of exclusion-logic sentences, and the Praxis language defines more than 1,000 parameterized actions, and a stress-test tool runs hundreds of instances of the game at once. Linden Lab cancelled the project in early 2014; social practices have no mechanic id and are proposed as social-practices.

appears in

the paper, 3 sections · 1 chapter
paper

4. A grammar of simulation games

linked in this section of the paper

paper
paper

5. The structure of the design space

linked in this section of the paper

paper
paper

Appendix A. Game catalog

linked in this section of the paper

paper
catalog

The catalog

listed with its year, developer, subgenre, and number of mechanics

book
ch 6

Chapter 6. Five ceilings

linked from the text

book

sources

3
Richard Evans, Emily Short (2014). Versu: A Simulationist Storytelling System. IEEE Transactions on Computational Intelligence and AI in Games 6(2)
Emily Short (2013-02-14). Introducing Versu. Emily Short's Interactive Storytelling
IFWiki contributors (2026). Versu. IFWiki

provenance

runs in log/runs
2026-10-24
created2026-10-24-catalog-gccatalog
2026-10-28
reviewed2026-10-28-verify-ai-charactersverification