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

parts

4 mechanics, as AI Dungeon does them

core · 2

narrative & generation

Generative content on demand

A language model continues the story text from a prompt of scenario, pinned memory, and recent turns; the See input generates an image that does not change play.

social relations

Natural-language interaction

Free-text input typed as Do (action), Say (dialogue), or Story (narration or facts), with blank input asking the model to continue.

supporting · 2

multiplayer & persistence

Content sharing

Players publish custom adventures and scenarios that others can start from.

time & pacing

Turn structure

Play alternates player input and model output; multiplayer (from April 2020) rotates turns among players' characters while the host can edit model output.

core loop

choose a setting -> type a Do, Say, or Story input -> model continues the text from recent story and pinned memory -> player undoes, retries, or edits the output -> next input

design notes

At runtime the model does all the work: each turn, the game assembles a prompt from the scenario premise, player-pinned memory, and recent story text, and a language model (GPT-2 with 1.5 billion parameters in AI Dungeon 2, GPT-3 through OpenAI's API for the premium Dragon model from July 2020) generates the next passage. There is no separate world state, inventory, or rules engine, so consistency lasts only as long as facts stay in the context window, and undo, retry, and edit are the player's tools for steering. Nick Walton built the first version at a BYU hackathon on a 126-million-parameter GPT-2 and released it in May 2019; Latitude relaunched it in December 2019. It is a boundary case: no system is simulated outside the model's text.

appears in

the paper, 3 sections · 6 chapters · 4 episodes
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 2

Chapter 2. Six layers

named in the text

book
ch 3

Chapter 3. Old parts

linked from the text

book
ch 4

Chapter 4. Families

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
ch 11

Chapter 11. What breaks

named in the text

book
ep 2

Where the parts came from

on screen at 5:43 after 2000

episode
ep 3

Families across genres

on screen at 4:20 odd couples

episode
ep 6

What AI shipped

on screen at 0:21 when the model is the game, 7:39 how it was received

episode
ep 10

What breaks

on screen at 4:48 trust

episode

sources

1
Wikipedia contributors (2026). AI Dungeon. Wikipedia

provenance

runs in log/runs
2026-10-24
created2026-10-24-catalog-gdcatalog