Universal Modder lets AI coding agents build mods for PC games

Summary

Universal Modder is a GitHub project that gives AI coding agents a shared workflow for modifying PC games that users own. It supports Claude Code, Codex, Cursor, Gemini CLI, GitHub Copilot, OpenCode, and other agents that read AGENTS.md. The workflow begins by searching prior field notes, identifying the game engine and version, and choosing a modding route; it then backs up saves, examines the real code, builds a working slice, generates assets, tests the result in the running game, packages it, and records what was learned. The project supplies skills in Agent Skills format, the um Python CLI, a fal MCP server for image, 3D, audio, and video generation, and engine-specific playbooks for technologies including Unity, Unreal, .NET/XNA, Godot, Bethesda, Minecraft, and native C++. Its knowledge base stores versions, routes, verification details, and troubleshooting notes that later agents can reuse. Examples include Terraria weapons and enemies, a new Age of Empires II civilization, and a Minecraft-through-GTA V passthrough mod. The project requires Python 3.10+, ffmpeg, and a fal API key for generated assets; Blender is needed for 3D-to-sprite rendering. It is limited to single-player and offline games, refuses online anti-cheat injection and DRM or ownership-check bypasses, avoids shipping game files or decompiled code, backs up saves, and asks before controlling input, changing game folders, or publishing. The repository is MIT licensed.