GitHub is a GOLDMINE for AI game developers. I picked 10 powerful open-source repos that make building 3D games with Claude Code and Codex ridiculously easier. Save these before your next project: 1. Gamedev Agent Skills Give Claude Code and Codex reusable game-development skills for engines including Godot, Unity, Unreal, and Three.js. github.com/gamedev-skills/aw… 2. MCP Unity Connect your coding agent to Unity. Create scenes, modify objects, assign materials, run tests, and read console errors through prompts. github.com/CoderGamester/mcp… 3. Godot MCP Let your AI assistant create scenes, add nodes, run Godot projects, and inspect debug output while building your game. github.com/Coding-Solo/godot… 4. TripoSR Turn a single image into a 3D model. Useful for prototyping props and exploring assets before refining them for your game. github.com/VAST-AI-Research/… 5. Drei Ready-made helpers for React Three Fiber: camera controls, environments, skies, shadows, and model loading for browser-based 3D games. github.com/pmndrs/drei 6. React Three Rapier Add physics to React Three Fiber games, including rigid bodies, collision detection, and joints, without writing a physics engine yourself. github.com/pmndrs/react-thre… 7. Yuka Build NPC behavior with steering, pathfinding, perception, and state-driven decisions. Give your characters more to do than stand around. github.com/Mugen87/yuka 8. Three.quarks Build particle effects for Three.js games, from sparks and smoke to magical trails. Includes a visual editor for designing effects. github.com/Alchemist0823/thr… 9. React Postprocessing Give React Three Fiber scenes a visual upgrade with bloom, depth of field, noise, and vignette effects. github.com/pmndrs/react-post… 10. Colyseus Build multiplayer features with rooms, matchmaking, reconnections, and automatic game-state synchronization between your server and players. github.com/colyseus/colyseus Which one are you using in your next game?