Ritmo skill
TypeScript ECS runtime for agent-built games: compiler errors suggest the fix and headless runs explain each value
- 148 ★ on the repository
- Last commit
- MIT
Minimal access
Why this level
- The agent edits the game source, so review the changes in version control
- An npm dependency pulls third-party code, so pinning the package version is useful
Install
- Works in
In your terminal, with SkillFoxx CLI
npx skillfoxx add skills/ritmoDetects the agents on your machine, shows the access level and pins the version.
Other ways to install
Access and checks
How we reviewMinimal accessThe tool runs nothing and makes no network calls.
- The agent edits the game source, so review the changes in version control
- An npm dependency pulls third-party code, so pinning the package version is useful
This is third-party code. Review the repository files before installing.
What it does
Ritmo is a set of packages for building games where an agent writes the code and a human directs mechanics and feel. The `@typeonce/ritmo` core has a fixed-step ECS runtime, seeded random and trigonometry with identical bits across machines. Systems get only the data access they declared. Packages around the core cover 2D math (vectors, angles, swept circle collision, flow fields), browser ticks and keyboard, gamepad, pointer and touch input, entity-to-render-node sync and a Pixi adapter. Type errors name the fix near their start, and headless runs show lints, invariants and why each value changed. The `packages/core/skills` folder holds the `ritmo`, `ritmo-prototype`, `ritmo-polish`, `ritmo-fx`, `ritmo-music`, `ritmo-sounds`, `ritmo-pixel-art` and `ritmo-onboarding` skills, plus playbooks for bug fixes, content, mechanics and netcode.
Who it is for. Indie developers of TypeScript games who hand code writing to an agent, and anyone who needs a deterministic simulation for tests and online play.
Good fit when
- An agent writes the game and you want compile errors that suggest the fix
- A simulation must give the same result on different machines for tests or networking
- You need a headless run to see why a value changed
- Rendering stays your own, Pixi or another, and ECS is only for logic
Not a fit when
- You need a ready engine with a scene editor and drawing: Ritmo does not draw
- The project is not in TypeScript or is below version 5.9
- You write the game by hand with no agent: part of the package value is built around its errors and skills
Example request
Add a movement system with Position and Velocity components to the game, run a headless pass of a hundred ticks and show why the position changedLimitations
TypeScript 5.9 or newer is required. Leave `noErrorTruncation` off: errors name the fix near the start of the message, while the full text sometimes prints a whole schema. Developing the repository itself lists Node 22 and pnpm. Drawing stays in your game, and the package and skill list is changing: the last commit is dated November 11, 2026. Skills have to be copied into the agent skills directory by hand, and the README has no ready installer.
How to disable. Remove the `@typeonce/ritmo` dependency from the project `package.json` and the `ritmo*` skill folders you copied into the agent skills directory.
FAQ
What is Ritmo?
A set of TypeScript packages: a fixed-step ECS runtime, math, input and render adapters, designed for agents that write the game code.
Does Ritmo draw graphics?
No, drawing stays in your game. The `ritmo-render` and `ritmo-pixi` packages only sync entities with render nodes.
Which skills are in the repository?
`packages/core/skills` holds ritmo, ritmo-prototype, ritmo-polish, ritmo-fx, ritmo-music, ritmo-sounds, ritmo-pixel-art and ritmo-onboarding.
Which TypeScript version is required?
Version 5.9 or newer, as stated in the README.
Which packages does Ritmo include?
The `@typeonce/ritmo` core, `@typeonce/ritmo-math`, the `@typeonce/ritmo-browser` layer, `@typeonce/ritmo-render` sync and the `@typeonce/ritmo-pixi` adapter.
Discussion
No questions or reviews yet.
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Comparison with similar tools
Cards that share the main search query, and how they differ.
| Tool | Official | Repository stars | Main difference |
|---|---|---|---|
| Ritmo (this card) | no | 148 | |
| Phaser | yes | 40,704 | a library for logic and deterministic simulation, with drawing left to your game |
| awesome-gamedev-agent-skills | no | 8,686 | a standalone runtime with skills in the repository and no list of links |
README in short
The README presents Ritmo as a toolkit for agent-driven game development: the human directs mechanics and feel and the agent writes the code. It gives a short TypeScript example with components, a movement system and a tick, then a table of packages. Skills appear in the repository structure.