# universal-modder

> Skills and a CLI that let AI coding agents mod PC games you own

- Repository: https://github.com/rehan-remade/universal-modder
- Category: Coding agents & dev tools
- Stars: 8,741 · Forks: 960 · Language: Python · License: MIT
- Experience: Some experience
- Page: https://ir.adyog.com/repos/rehan-remade/universal-modder/

Modding a game usually means working out the engine, finding the right loader, reading decompiled code, making art and sound, and testing in the running game. This project packages that work as skills in the Agent Skills format, so an agent can follow the same loop each time.

The loop starts with a search of a knowledge base of field notes, then recon of the game, a safe lab with backed-up saves, reading the real code, building one working slice, generating assets, testing in the game, recording and packaging. At the end, the agent can write a field note and open a pull request so the next agent starts with what it learned.

It works with several agents: Claude Code, Codex, Gemini CLI, Copilot, Cursor and OpenCode. Asset generation uses fal, which needs an API key. The README also names ComfyUI for local images and two paid sprite services as options.

## What it does

- **Skills for the whole modding loop**: Skills cover game recon, reverse engineering, asset generation, an asset pipeline, game automation, showcase videos, mashup mods, publishing and porting. The main skill includes playbooks for many engines, such as Unity, Unreal, Godot, Source and GameMaker.
- **Field-note knowledge base**: The knowledge folder holds notes on how specific games were modded, with working versions, the route taken, how it was verified and the gotchas. The um kb commands search, create, check and submit notes.
- **The um CLI**: A Python command-line tool for fal asset generation, key storage, knowledge base search and pull requests. It also supports ComfyUI, Sprixen and Voidless for images and sprites.
- **fal MCP for art, 3D and audio**: The fal tools generate sprites, textures, image-to-3D models, sound effects, music, voice and cutscene video. The asset pipeline then fits them to a game's exact frame and palette needs.
- **Optional three-agent team**: For long mods, an orchestrator checks the work of a game worker, which touches the running game, and an offline worker, which does not. The README warns this uses several times the tokens of one agent.

## What you could build

- Add a new weapon or item with generated sprites to a game like Terraria.
- Research what engine a game uses and whether anyone has modded it before.
- Port content from one game into another, such as a vehicle into Minecraft.
- Record and cut a showcase video of a finished mod.
- Write up a field note on a mod you made so others can build on it.

## Who it's for

Suits hobbyist modders and developers who already use an AI coding agent and own the games they want to mod; you should be comfortable with a terminal, Git and Python 3.10+.

## Get started

Install the plugin for your agent. For Claude Code, run the two plugin commands below. Install the um CLI with uv, add a fal API key with um fal key set if you want generated assets, then ask your agent to mod a game. You also need Git, Python 3.10+ and ffmpeg.

```
/plugin marketplace add rehan-remade/universal-modder
```
```
/plugin install universal-modder@universal-modder
```
```
uv tool install git+https://github.com/rehan-remade/universal-modder
```

Tags: game-modding, claude-code, agent-skills, reverse-engineering, mcp