Universal Modder plugin
universal-modder
A plugin and skills for mods to games on your PC: engine recon, code analysis, fal assets, testing in the running game and a showcase video
- 9,174 ★ on the repository
- Last commit
- MIT
Broad access
Why this level
- Launches games, controls the window, mouse and keyboard, stops processes by PID and installs mod loaders into the game folder
- Reads game memory and executables through reverse engineering tools: ILSpy, Ghidra, Cheat Engine and Frida
- Holds the fal key and sends the service requests to create images, models, sound and video
Install
- Works in
In your terminal, with SkillFoxx CLI
npx skillfoxx add plugins/universal-modderDetects the agents on your machine, shows the access level and pins the version.
Other ways to install
Access and checks
How we reviewBroad accessThe tool can change data, run commands or handle secrets.
- Launches games, controls the window, mouse and keyboard, stops processes by PID and installs mod loaders into the game folder
- Reads game memory and executables through reverse engineering tools: ILSpy, Ghidra, Cheat Engine and Frida
- Holds the fal key and sends the service requests to create images, models, sound and video
This is third-party code. Review the repository files before installing.
What it does
Universal Modder is a set of skills, the `um` utility and the fal MCP server that let Claude Code, Codex, Cursor, Gemini CLI, GitHub Copilot and OpenCode make mods for games you own. The main skill, `mod-any-game`, walks the agent through the same loop every time: search the shared knowledge base for similar notes, recon the game and choose a route, set up a safe lab with backed-up saves, read the real code, build one working slice of the mod, generate assets, verify in the live game, record video, package, and leave a note for the next agent. For each engine the repository holds a separate playbook: Unity, Unreal, .NET and XNA (Terraria, Stardew Valley), Godot, Source, Bethesda, Minecraft, Age of Empires II and others. The `um scan` command finds Steam, Epic and Xbox installs and identifies the engine, version, code type, anti-cheat and save folders. Then `um fal` produces sprites with real transparency, textures, 3D models, sound, music and voice, `um sprite` and `um render3d` fit pictures to the engine's frames, `um win` launches the game, takes screenshots and sends input to its window, `um backup` handles rollbacks, `um video` cuts the showcase clip, and `um publish check` blocks shipping game files, decompiled code and keys. Separate skills cover reverse engineering (ILSpy, Ghidra, Cheat Engine, Frida), porting an old mod to a new version and games inside games. The `knowledge/` folder holds notes that agents write for each other: versions, route, verification and gotchas. The `examples/` folder includes a Terraria mod, a new civilization for Age of Empires II and real Minecraft inside GTA V.
Who it is for. For players and developers who want an agent to build a mod for a game in their library: new weapons, units, mechanics or a port of a mod to a fresh version.
Good fit when
- You need a mod for Terraria, Minecraft or Age of Empires II with new weapons, enemies or a civilization, and you want the idea taken to a working result in the running game
- An old mod was written for Forge 1.7.10 and has to move to Fabric 1.20.1 with a mapping table and layer-by-layer checks
- You do not know which engine the game in `C:\Games\Foo` uses, whether it has anti-cheat and whether anyone has modded it before
- The mod needs assets: sprites, textures, 3D models rendered into frames for the right camera angle, sounds and music
- You want to show a finished mod: the skill records the game window with only the game's own audio and cuts a video
Not a fit when
- You want a cheat, an aimbot or an anti-cheat bypass for an online game: the skills refuse this, and the line is drawn in `skills/mod-any-game/references/safety.md`
- The game is protected by Denuvo or another DRM and a loader needs the executable patched around it: the kit stops in that case
- You want a ready mod from a catalog rather than a new one: the project does not distribute game files or other people's mods
- The game does not run on Windows: the `um win` commands for launching, screenshots and input are built for Windows, including from WSL
Example request
Mod Terraria: add a homing missile launcher and a tactical nuke that craters the world. Make the sprites with fal and check everything in the running gameLimitations
The tool is built for games you own, in single-player, offline or on a server you run yourself. This is reverse engineering and memory work: apply it only to games and data you have the right to. The skills refuse to inject code into online clients with anti-cheat, write cheats against other players and bypass protection and ownership checks.
Assets need an fal API key, stored with `um fal key set`; without a key a local ComfyUI server makes images, and `um sprixen` needs the paid Sprixen service with its own key. You need Git, Python 3.10 or newer and ffmpeg, and Blender for rendering 3D into sprites.
The `um` command lands on PATH only with the Claude Code plugin; for Codex, Cursor, Gemini CLI and OpenCode it is installed separately with `uv tool install`. The three agents in the kit for long mods spend several times more tokens than one.
The author lists the universalmodder.com mod hub as planned, not as working.
How to disable. In Claude Code run `/plugin uninstall universal-modder@universal-modder`, in Codex remove the plugin with the `codex plugin` command, and for an `npx skills add` install delete the skill folders from `.agents/skills/`. Remove the `um` utility with `uv tool uninstall universal-modder` and delete the stored fal key by hand.
FAQ
How do I make a game mod with Claude Code?
Install the plugin with `/plugin marketplace add rehan-remade/universal-modder` and `/plugin install universal-modder@universal-modder`, open a project and describe the idea in one sentence, for example a new weapon for Terraria. The `mod-any-game` skill identifies the engine through `um scan`, picks a route, builds a slice of the mod and checks it in the running game.
Which games will the agent refuse to mod?
Online games with anti-cheat: EasyAntiCheat, BattlEye, Vanguard, Ricochet and others in the `safety.md` list. What stays allowed is official tooling (workshops, map editors) and an official offline mode without anti-cheat. The skills also reject hardware ID spoofing and bypassing copy protection.
Do I need an fal key and what does it cost?
Images, 3D, sound and video through fal need a key from fal.ai/dashboard/keys. Enter it with `um fal key set`: on Linux it goes to the system keyring, elsewhere into an owner-only `~/.secrets/fal-key` file. fal sets its own pricing, and the project description does not quote it. Without a key you keep local ComfyUI and browser sign-in through OAuth.
What is in the knowledge/ base and can I add my own note?
Agents write there how specific games were actually modded: versions, route, what the engine really does, verification and gotchas. Search with `um kb search "grand theft auto"`, create your own note with `um kb new` and send it with `um kb pr` after your approval. Downloaded game files and decompiled dumps are not accepted in the repository.
Can an old mod be ported to a new version of the game?
The `port-a-mod` skill does this: one pinned source, a private decompile, data from a script, checks by unit and layer, and a mapping table from Forge 1.7.10 to Fabric 1.20.1. You may publish the result only if the original's license allows it.
How do I run the um command in Codex or Cursor?
The Claude Code plugin puts `um` on PATH itself and other agents do not. Install the utility once: `uv tool install git+https://github.com/rehan-remade/universal-modder`. Inside a clone of the repository `export PATH="$PWD/bin:$PATH"` is enough.
Discussion
No questions or reviews yet.
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Comparison with similar tools
Entries that share the main search query, and how they differ.
| Entry | Official | Authentication | Repository stars | Main difference |
|---|---|---|---|---|
| Universal Modder (this entry) | no | 9,174 | ||
| Agent Sprite Forge | no | 4,633 | makes only 2D sprites, animation sheets and layered maps for games | |
| Ghidra MCP Server | no | not required | 5,976 | an MCP server for the Ghidra disassembler with hundreds of reverse-engineering tools |
README in short
The project description opens with an install table for Claude Code, Codex, Gemini CLI, VS Code with Copilot, Cursor and OpenCode, then explains the fal key and the requirements. Next come sample requests, a ten-step loop, the knowledge base with example notes, tables of skills, three agents and `um` commands, a section on mods built with it and the safety rules. The repository holds engine playbooks, example mods for Terraria, Age of Empires II, Minecraft with GTA V and other games, an OpenCode plugin and tests for the utility.
README badge
Original SKILL.md
---
name: mod-any-game
description: Mod a PC game the user owns, taking an idea to working in the real game and recorded. It covers new items, weapons, enemies, bosses, units, civilizations, mechanics, art, sound, VR and cross-game mashups. Use when the user wants to mod, extend, hack on, reverse engineer or mash up a game ("add a nuke to Terraria", "make a new civ for Age of Empires", "put Minecraft inside X", "can I mod this game?"). It covers recon (engine, loaders, anti-cheat), choosing the route, a safe lab, a first vertical slice, fal-generated assets, in-game verification and a showcase clip.
---
# Mod any game
You are the modder. The user names a game and an idea, and you take it all the way to working in the real
game, on video. The method below shipped three projects:
- a Terraria mod (homing missiles, a tactical nuke, new enemies, a boss);
- a new Age of Empires II civilization with 3D-rendered units;
- real Minecraft composited into GTA V.
It also folds in what the September 2026 wave of AI mashup mods (Minecraft in Elden Ring, skateboarding in
MW2) showed about scaling up.
- Case studies: `references/case-studies.md`.
- Code: `examples/`.
- Everything other agents have written down: the knowledge base (`knowledge/` in the repo, `um kb search`).
## Your tools
`um` is the toolkit CLI (`bin/um` in the repo). The Claude Code plugin and a clone opened in Claude Code put it
on PATH; other agents' plugin installs don't. If `command -v um` finds nothing, use `bin/um` in a clone, or
install it once: `uv tool install git+https://github.com/rehan-remade/universal-modder` (or `pipx install ...`).
Every group has `--help` with examples.
| Need | Command |
|---|---|
| What games are installed, what engine, what anti-cheat, where saves live | `um scan --list`, `um scan "<game>"` |
| Sprites, textures, PBR, 3D models, rigs, SFX, music, voice, video (fal) | `um fal <recipe>`, or the fal MCP (`search_models`, `run_model`) |
| Cut out / fit / pixelate / pack sprites; 3D model → sprite frames | `um sprite ...`, `um render3d ...` |
| Launch, screenshot, click/type, record a Windows game (also from WSL) | `um win ...` |
| Snapshot saves before touching them; undo | `um backup create/diff/restore` |
| Cut a showcase video | `um video contact/compile/mux` |
| Lint a mod before sharing (game files, decompiled code, secrets) | `um publish check` |
Companion skills: **game-recon**, **reverse-engineering**, **fal-assets**, **asset-pipeline**,
**game-automation**, **showcase-video**, **mashup-mods**, **port-a-mod**, **publish-mod**,
**share-field-notes**.
## The loop
### 0. Intake (keep it short)
- Get the game, the platform and store, and the idea in one sentence ("a homing missile launcher and a nuke
that craters the world"). Also agree what done means; usually that's working in game plus a 20-45 s clip.