Chasm

A generative interactive fiction text adventure

Chasm is a single-player text adventure game in a world you can specify. It uses generative artificial intelligence (LLMs) to generate scenes and characters as you play.

Unlike simply role-playing with a chatbot, important state persists (locations, characters, dialogue, events and so on) between sessions. Each world is simply a directory of markdown files: a language model narrates your story through the pi coding harness (and inherits its architecture).

Play is single-player, but a world is a git repo: you can distribute it and someone else can continue it.

Install

Requires Node.js 18+, npm, git, and Python 3.

Quick install (one-liner):

curl -sSL https://chasm.run/web-install.sh | bash

Or clone manually:

git clone https://github.com/atisharma/chasm.git
cd chasm
./install.sh --local

If pi is not on your PATH, the installer will install it via npm. On a fresh install it asks whether to reuse your existing pi model config (~/.pi/agent/models.json); answering yes copies it to ~/.local/share/chasm/models.json (more generally $XDG_DATA_HOME/chasm/models.json). Each game inherits this file via a symlink created by chasm new.

When starting you'll need to configure a model by typing /login (unless you reused your pi config during install).

Chasm requires a model with tool-use support (function calling). Good choices as of 2026: Kimi K2.5, Mistral Medium 3.5, Sonnet 4.5 via OpenRouter. You can configure local models via vLLM, for which you'll have to edit ~/.local/share/chasm/models.json (more generally $XDG_DATA_HOME/chasm/models.json; see the pi documentation to set up models). Each game inherits this file via a symlink created by chasm new. Qwen 3.6 27b, Gemma 4 work well.

During play, switch models with Ctrl+L.

Quick Start

chasm new sunken-quarter
chasm play sunken-quarter

Game names must use only letters, digits, hyphens, and underscores (no spaces). Use kebab-case (sunken-quarter) or snake_case (sunken_quarter).

First launch triggers a short Q&A — title, setting, genre, tone, a unique rule, and starting place. The narrator then drops you into the world.

Resume later: chasm play sunken-quarter.

Updating

chasm update                 # refresh the installed template + CLI
chasm update sunken-quarter  # refresh tooling files in one game
chasm update --all           # refresh tooling files in every game
chasm update --all --force   # ...overwriting locally-modified tooling files

chasm update pulls the latest template and CLI from the canonical repo into ~/.local/share/chasm/ ($XDG_DATA_HOME/chasm/; your models.json config there and all games are preserved). chasm update GAME refreshes only the managed tooling files in an existing game (settings.json, bin/, .pi/extensions/, .gitignore, memory/AGENTS.md, APPEND_SYSTEM.md) and commits them as [chasm] Update template files. Game content — memory/ world state (places, characters, events, WORLD.md), sessions, and the models.json symlink — is never touched. Managed files you have edited locally are skipped with a warning unless --force is given.

In-Game Commands

Type natural language to act in the world. The narrator interprets your commands and responds in second-person prose.

Command	What it does
Ctrl+L	Switch models mid-session
Ctrl+O	Expand/collapse tool output
/save	Force a save of the game state
/sync	Force the narrator to re-read and persist state (use if the model forgets)
/compact	Compact the context (use if the model's beginning to forget its instructions, or getting confused)

How It Works (Briefly)

A Chasm world is a git repo of markdown files. The narrator reads state, interprets your commands, and writes the story back. Everything is visible and editable. See docs/architecture.md for the full picture.

Troubleshooting

Model not configured: Run pi /login, or edit ~/.local/share/chasm/models.json ($XDG_DATA_HOME/chasm/models.json) manually — each game inherits it via a symlink.

First launch shows placeholder text: Run chasm play again; the bootstrap runs only when WORLD.md is uninitialised.

Permission denied on chasm: Ensure ~/.local/bin is on your PATH, or use the full path.

Disclaimer

There is no good way to moderate the actions and writing of language models. Chasm could offend you, embarrass you in front of your mother-in law, execute rm -rf ~ or even execute your kitten. You must check prompts that other people provide for such instructions. No guarantees thereof are offered.

License

MIT. See LICENSE.