Independent guide · live from GitHub
Universal Modder: point your AI agent at any game you own.
universal-modder is a free, open-source toolkit that teaches Claude Code, Codex, Cursor and Gemini CLI how to mod PC games: recon the engine, reverse-engineer the code, generate art, 3D and sound with fal, test in the running game, and leave notes for the next agent.
- 5.8kGitHub stars
- 78game field notes
- 12engine playbooks
- 6supported agents
Synced with GitHub Oct 9, 2026
What it is
A modding method your agent can follow, not a "make mod" button
Universal Modder is a toolkit of 11 Agent Skills, the um CLI, a fal MCP server and a shared knowledge base that agents write for other agents. It was built by Rehan from real Claude Code sessions modding Terraria, Age of Empires II and GTA V × Minecraft, and released under the MIT license on Sep 30, 2026.
Your agent still does the work. The toolkit gives it the playbooks, tools and prior art so it stops guessing: which loader to use, where the saves are, what the engine actually does, and how to know the mod really works.
Install
Pick your agent
Every route gets the same skills, the fal MCP server and the um CLI.
Claude Code
/plugin install universal-modder@universal-modder
Step-by-step →Codex
codex plugin add universal-modder@universal-modder
Step-by-step →Gemini CLI
gemini extensions install https://github.com/rehan-remade/universal-modder
Step-by-step →Cursor
Cursor Marketplace, or clone the repo
Step-by-step →VS Code / Copilot
Chat: Install Plugin From Source
Step-by-step →OpenCode
clone, then run opencode inside it
Step-by-step →/plugin marketplace add rehan-remade/universal-modder
/plugin install universal-modder@universal-modderHow it works
The same 10-step loop on every game
The mod-any-game skill runs this loop whatever you ask for.
- Search the knowledge baseStart from what other agents already learned about this game or engine.
- Recon, then pick a routeEngine, version, loaders, anti-cheat and saves → a MODDING_PLAN.md.
- Set up a safe labSaves backed up, separate profile, fixed window size.
- Read the actual codeILSpy, Ghidra, Cpp2IL, Frida: not guesses about the code.
- Build one working sliceOne item, unit or mechanic, end to end, before scaling.
- Generate assetsSprites, textures, 3D, SFX and music from fal, fitted to the engine.
- Verify in the real gameScreenshots, logs and test scenes in the running game.
- RecordCapture the window with only the game's audio.
- PackageLint for game files, decompiled code and leaked keys, then ship.
- Write a field noteGotchas and exact versions go back into the knowledge base.
Game library
78 field notes across 42 games
Each game page lists what agents actually built, the versions that worked, and the gotchas they hit.
World of Warcraft
10 notes · 9 working · last 2026-10-04
Custom AzerothCore modules for a solo-with-bots WotLK server: offline gathering, auction payout and restock, mail and progression fixes
Test Drive Unlimited 2
7 notes · 1 working · last 2026-10-06
TDU2 vehicle physics: the Havok 5.5.0 packfile format inside .bnk containers
Baldur's Gate 3
6 notes · 6 working · last 2026-10-05
Weapons: porting a Skyrim dagger and scabbard, fixing a modded sword's sheath height with a Dummy_Sheath bone, and visible stowed shields for modded shields
Minecraft
6 notes · 6 working · last 2026-10-07
Kindred: Local LLM AI companion with Ollama, bounded inference, autonomy, and memory
Watch Dogs
4 notes · 1 working · last 2026-10-06
Watch Dogs 1: editing .feu/.gfx UI components and rebuilding entitylibrary_rt.fcb
Assassin's Creed IV Black Flag
2 notes · 1 working · last 2026-10-06
A visible, driven second character in AC4 single-player (co-op ghost avatar)
Dragon's Dogma 2
2 notes · 2 working · last 2026-10-05
Dimension Door: aimed teleport spell with a scripted arrival camera (REFramework Lua)
Half-Life
2 notes · 1 working · last 2026-10-05
Half-Life 1's weapons and monsters as a Minecraft Fabric mod, from a GoldSrc model converter
Naruto Shippuden: Ultimate Ninja Storm 4
2 notes · 1 working · last 2026-10-05
Naruto Storm 4: free-for-all for 4-6 teams with native UI, by controlling the duel's side/role lookups
Palworld
No field note yet · Unreal Engine 5
How you would start, and how this differs from the UEVR "universal VR mod".
Cost
Free code, pay-per-asset art
A default sprite is about $0.21 on fal, a 3D model $0.25–0.35, sound $0.002/second. A small mod's assets come to a few dollars.
Cost calculator →Safety
Games you own, nobody else's match
No anti-cheat bypass, no cheats against players, no shipped game files, saves backed up first, and it asks before taking control.
Rules & ban risk →Compare
vs plain agents, loaders and look-alikes
How it differs from a bare Claude Code session, BepInEx/UE4SS, Vortex/MO2 and the similarly named universal-game-modder.
See comparisons →Latest on GitHub
What changed recently
- 2026-10-08kbreading old ForzaTech burG .modelbin containers and the MakeH2O lineage (#134)
- 2026-10-08kbThe Witcher 3 Remastered: .bundle container and CR2W, decoded (The Witcher 3) (#133)
- 2026-10-08kbDetroit Become Human SEGS/DATA_CONTAINER editing in Blender (#129)
- 2026-10-08kbResident Evil 2's picture composited into Minecraft with depth (Minecraft) + D3D12 readback technique (#132)
- 2026-10-08otherAdd mashup technique notes, a table of mashup projects, and a route planning checklist for mashup-mods (#135)
- 2026-10-08knowledgeadd 40 field notes from a reverse-engineering workspace (#106)
Frequently asked questions
What is Universal Modder?
Universal Modder (universal-modder on GitHub) is an open-source kit of Agent Skills, a Python CLI called um, a fal MCP server for generated art, 3D and audio, and a shared knowledge base of field notes. Together they teach an AI coding agent how to mod a PC game you own: find the engine, pick a route, read the real code, build the mod, test it in the running game, and write down what it learned.
Is Universal Modder free?
The toolkit is free and MIT licensed. You still pay for your AI agent (for example a Claude Pro or Max plan for Claude Code) and, if you want generated sprites, 3D models or sound, for fal API usage. A small mod's assets typically cost a few dollars. See the cost breakdown.
Which AI agents does Universal Modder work with?
Claude Code, OpenAI Codex, Gemini CLI, GitHub Copilot in VS Code, Cursor and OpenCode all have documented install routes. Any other agent can use it by cloning the repo or installing the skills with npx skills add. See the install guide.
Can it really mod any game?
No tool can mod literally every game. It ships 12 engine playbooks (Unity, Unreal, .NET/XNA, Godot, Source, Bethesda, Minecraft, AoE2, RE Engine/FromSoft/GTA and more) and a knowledge base of real attempts. How far you get depends on the engine, whether a mod loader exists, and how protected the game is. Online games with anti-cheat are off-limits by design.
Will I get banned for using it?
The skills tell the agent to refuse online games with anti-cheat, cheats against other players and DRM bypasses, and to back up saves before touching them. Stay in single-player, offline modes or servers you host. These are instructions to the agent, not a technical lock, so the responsibility is still yours. More on the safety page.
Does Universal Modder work on Mac or Linux?
Install, the knowledge base, sprite processing, backups and publish checks run on macOS and Linux. The game-automation part (um win: launch, screenshot, input, recording) targets Windows, natively or from WSL. Most PC games are Windows games anyway.
Is universal-modder.dev the official website?
No. This is an independent guide. The only official source is the GitHub repository rehan-remade/universal-modder, and the project does not list an official website. Install from there; nothing on this site asks for keys, payment or a separate download.
Is it the same as universal-game-modder or the Universal VR mod?
No. universal-game-modder is an unrelated MCP server published on npm, and the "universal VR mod" people use for Palworld is UEVR. See Universal Modder vs universal-game-modder.