melonJS Ships 25 Agent Skills for Its Game Engine

Games built by AI have a nasty failure mode: the code runs, but the game misbehaves without raising an error. melonJS, the open-source 2D and 3D HTML5 game engine, ships a set of agent skills that teach your coding assistant the engine's conventions — and, more usefully, the mistakes that fail silently rather than raising an error.

Why This Skill Matters

melonJS 2 is a fully featured game engine for indie developers — its feature set includes perspective and orthogonal cameras, GPU-accelerated tilemap rendering, post-processing effects, custom shaders, 3D mesh support, and polygon-accurate physics, running on WebGPU, WebGL 2, or Canvas2D with automatic fallback. The whole engine is about 250 KB minzipped, with no dependencies.

The skills are versioned with the engine and ship inside the npm package at node_modules/melonjs/skills/, so a copy matching the exact release you are running is always on disk. The set covers the engine surface by topic, including melonjs-getting-started, melonjs-tilemaps, melonjs-physics, melonjs-sprites-and-animation, melonjs-scenes-and-state, melonjs-effects-and-shaders, melonjs-3d, and melonjs-performance — 25 skill directories in total.

Installation

One command installs the skills into whatever assistant your project uses:

npx skills add https://github.com/melonjs/melonJS/tree/master/packages/melonjs/skills

The installer detects the assistants in your project, installs one copy of each skill under .agents/skills/<skill-name>, and symlinks that copy into every assistant's own directory — so .claude/skills/melonjs points back at .agents/skills/melonjs and there is nothing to place by hand. It reports the assistants it covers as it runs (77 of them at the time of writing). Add -a claude-code -a cursor to target specific ones.

Real Workflow: Wire the Skills into a Game Project

1. From your game project's root, run the install command above.
2. Read the installer's report: it lists the assistants it detected and covered, and any agent already present — Claude Code, Cursor, and the rest — now resolves the melonjs skills.
3. Start a coding session and ask for engine work through the skills' own vocabulary: a tilemap scene with collision shapes, a sprite with animated movement, or a camera that follows the player.

The set also includes an AGENTS.md for anything following that convention (Codex, Cursor, Gemini CLI); GitHub Copilot reads the same content from .github/copilot-instructions.md. Per the README, it names the three rules that produce code which runs and is wrong, and links the engine's API index. If you already keep an AGENTS.md, paste its sections into yours.

Tips

• The command installs from master. To pin the skills to the release your game runs on, point the URL at that tag instead of master.
• The skills are plain markdown and can be read by any agent — or by you. Reading them before a session tells you which engine conventions the agent will follow.
• For anything the skills do not cover, the complete API is indexed for agents at llms.txt — every exported class, function, and type with a one-line summary, regenerated on every docs build.
• Because a copy ships inside the npm package, an offline project can point its agent at node_modules/melonjs/skills/ directly.

When Not to Use This

These skills document one engine's conventions. If your project uses Phaser, PixiJS, or raw Canvas, the melonjs skill set is the wrong guidance for it. And they complement — not replace — the engine's own documentation and API reference when you need exhaustive detail.

See the leaderboard for more skills.