debuffjp/debuff

debuff is an open-source toolkit for 2D browser games that handles the basics for you (the game loop, controls, sound, levels, testing, shipping) so you get to that game sooner and spend your time on what makes it yours.
The groundwork, done. Start from a running game in under a minute. Crisp pixels on every screen, keyboard, touch and gamepad, sound that plays, levels from Tiled or LDtk, and a build you can put anywhere on the web, game portals like Poki and CrazyGames included (publishing guide).
Tune it until it feels right. Speeds, timings and other feel values become live sliders in the dev panel, with undo.
When something breaks, it tells you. Errors say whose bug it is and point at the line. Replays and scenario tests bring a bug back exactly, so you can fix it and move on.
Room to grow. Small (the starter ships at about 19 kB) and fast: its renderer, spryte, draws moving sprites 2-4x faster than the most popular 2D web renderer, at an eighth of its size: 800,000 at 60 fps on our test laptop, against 200,000 (benchmarks, run them yourself), so the engine doesn't hold your idea back.
Agents help if you want them, you decide. Coding agents can play the game you have open, read what's happening and check their changes. Creative calls stay with you.
> Status: 0.9, early development. APIs will change, and feedback from real games shapes them.
## Try it
You need Node.js 22 or newer.
bash
npm create debuff@latest my-game
cd my-game
npm install
npm run dev
Open the URL it prints, then press in the game for the dev panel. Edit src/main.ts and the game reloads. The first command asks which template you want. Base templates are starting points for your own game: basic (the minimal starter), topdown (a tile world seen from above), isometric (a 2:1 grid), sidescroller (run and jump) and pointclick (rooms, hotspots and an inventory), all but the first with pixel art drawn in tenten. Examples are finished small games to learn from: platformer, mossfell (a top-down adventure) and squish (a match-3 that plays well on phones). Skip the question with -- --template . pnpm, Yarn and Bun work too (pnpm create debuff, and so on).
New projects include a .mcp.json, so a coding agent like Claude Code can play and inspect the game you have open, and draw its pixel art with tenten. See the agent guide.
Working on debuff itself? Clone the repo, then run npm install and npm run build. cd templates/platformer && npx debuff dev runs a template against your local packages, and the repo's .mcp.json points the MCP server at it. See CONTRIBUTING.
## Why not just canvas and JavaScript?
| | Raw canvas + JS | debuff |
| Sprites at 60 fps | ~5,000 | ~100,000 one call each, ~800,000 in bulk (spryte: WebGL2 with a Canvas 2D fallback) |
| Small game, shipped | what you write | ~19 kB brotli for the starter, everything included |
| A crash in update | the loop dies silently | stops, says whose bug it is, links the source line |
| Tuning feel | edit, reload, replay | sliders while you play, with undo and copy back to code |
| AI agents | read code and guess | play your game: state, frames and errors, and you see what they did |