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

parts

7 mechanics, as Generative Agents (Smallville) does them

core · 3

agents & behavior

Daily schedules

Each morning the model drafts a day plan of about five to eight broad chunks, decomposed into hour-long and then 5-15 minute actions that agents revise when they react to events.

social relations

Gossip propagation

Information spreads only through agent conversations; over two game days awareness of a mayoral candidacy rose from 1 to 8 agents and of a party from 1 to 13, with 6 of 453 awareness answers hallucinated.

agents & behavior

Memories and thoughts

Each agent's memory stream stores observations, plans, and reflections as text; retrieval ranks them by recency (0.995 decay per game hour), model-rated importance (1-10), and embedding relevance, and reflections fire when summed importance exceeds 150.

supporting · 4

information & legibility

Agent inspection

Researchers interview agents and read their memory streams to evaluate believability.

narrative & generation

Generative content on demand

Plans, dialogue, importance ratings, and reflections are all generated by gpt-3.5-turbo calls at runtime.

social relations

Natural-language interaction

Users address agents in natural language as a persona or as the agent's inner voice, and can rewrite the status of objects in natural language.

social relations

Relationship values

Agents form acquaintances through conversation; network density rose from 0.167 to 0.74 over two game days.

core loop

agents perceive nearby events and objects -> observations enter the memory stream -> retrieve memories by recency, importance, and relevance -> plan the day and react -> converse and act -> reflections summarize memories -> plans and relationships change

design notes

Park and colleagues replace authored behavior trees with a loop of language-model calls on gpt-3.5-turbo. Every observation is stored as text with timestamps; retrieval scores memories by recency (decay 0.995 per game hour), importance (rated 1-10 by the model when stored), and embedding relevance, each normalized and weighted equally. When the summed importance of recent events passes 150 (two or three times a day) the agent writes reflections, and plans are decomposed from a day outline into hour and 5-15 minute chunks. Seeding one agent with the intent to host a Valentine's Day party led to 13 of 25 agents hearing about it and five attending over two game days, at a cost of thousands of dollars in API credits. The open-source release steps the town 10 game seconds per step.

appears in

the paper, 4 sections · 3 chapters · 2 episodes
paper

2. Method

linked in this section of the paper

paper
paper

3. The catalog

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 3

Chapter 3. Old parts

linked from the text

book
ch 6

Chapter 6. Five ceilings

linked from the text

book
ch 7

Chapter 7. What shipped

linked from the text

book
ep 2

Where the parts came from

on screen at 5:51 after 2000

episode
ep 5

The five ceilings

on screen at 5:54 minds made of formulas, 6:40 lifting one ceiling spends another

episode

relations

1 stored edges
influenced by

claims

1 with sources
c01high

In the two-day end-to-end run, relationship network density rose from 0.167 to 0.74 and five agents attended the Valentine's Day party.

network density increasing from 0.167 to 0.74

Section 7.1.2, Results

src-park-2023-generative-agents

sources

2
Joon Sung Park, Joseph C. O'Brien, Carrie J. Cai (2023-04-07). Generative Agents: Interactive Simulacra of Human Behavior. UIST '23 (ACM Symposium on User Interface Software and Technology)
Joon Sung Park (2023). joonspk-research/generative_agents. GitHub

provenance

runs in log/runs
2026-10-24
created2026-10-24-catalog-gdcatalog
2026-10-25
reviewed2026-10-25-contributor-readinessmaintenance
2026-10-28
reviewed2026-10-28-verify-ai-charactersverification