Guide · Agent skill
How to use the Mod Any Game agent skill: install and first mod
Updated · written with AI from the project's own documentation and checked against our catalogue data
The Mod Any Game skill (mod-any-game) is an agent skill that walks an AI agent through modding a PC game you own, from an idea to a working change you can see in the real game and record on video. It is aimed at hobbyist modders, developers learning how mod loaders and game data fit together, and creators who want a proof-of-concept clip. After this guide you will know what the skill does, how to install it, how to ask for work in plain language, and what it needs before it can run.
Mod Any Gamerehan-remade/universal-modder · MIT Download the skill Quick start
- 1Download and unzip the skill. Download the ZIP from the skill's page and unzip it into ~/.claude/skills/ or a project's .claude/skills/ folder, or upload it under Settings → Capabilities → Skills in the Claude apps.
- 2Install the um CLI. Check with command -v um. If it is missing, install it with uv tool install git+https://github.com/rehan-remade/universal-modder, or with pipx install using the same repository.
- 3Confirm your requirements. Check you have a Windows PC for in-game launch and automation, the loader the game needs, and fal API access if you want generated art or sound.
- 4Describe the game and idea. Make one request in plain language, naming the game and the change, such as adding a weapon or enemy.
- 5Scan the game. Let the agent run um scan to find the engine, anti-cheat, loaders and save folders, then read the matching playbook.
- 6Back up saves and choose a route. Create a backup with um backup create before the first modded launch, then pick the least invasive route and log it in MODLOG.md.
- 7Verify and record. Build a small slice, confirm it works in the real game from screenshots, and optionally cut a 20 to 45 second showcase clip.
What is an agent skill, and what does this one make the agent do?
An agent skill is a folder of instructions and supporting files that an AI agent loads when a task matches the skill's description. This skill's main file is SKILL.md, and it ships with reference playbooks for specific engines and a set of case studies.
Once installed, the agent follows a full modding workflow: it checks the game's engine, mod loaders and anti-cheat, picks the least invasive way to add your idea, backs up your saves, reads the game's code and data, builds a small working slice, and verifies it in the running game with screenshots and input automation. It can also generate art and sound through the fal service, cut a showcase video, and keep a journal of progress in MODLOG.md.
- Recon: engine, loaders, anti-cheat and save locations
- Route choice: data files, loader API, managed-code patching, native hooks, or a mashup
- Safety: backups and a separate lab profile before the first modded launch
- Verification in the real game, with a showcase clip if you want one
Install the mod-any-game skill
Download the ZIP from the skill's page on this directory and unzip it. For a personal setup, place the unzipped folder in ~/.claude/skills/. To limit it to one project, place it in that project's .claude/skills/ folder instead.
If you use the Claude apps, you can upload the ZIP instead: open Settings, go to Capabilities, then Skills, and add it there.
- Personal install: ~/.claude/skills/
- Project install: .claude/skills/ inside your project
- Claude apps: Settings → Capabilities → Skills, then upload the ZIP
Install the um command-line tool
The skill uses a command-line tool called um for scanning games, backups, fal generation, Windows automation and video. It is installed from the GitHub repository with Python's uv or pipx. Check whether it is already available first.
If the command is not found, install it with uv. If you prefer pipx, the source gives the same repository with pipx install. Every um command group has a --help flag with examples.
- Check: command -v um
- Install with uv: uv tool install git+https://github.com/rehan-remade/universal-modder
- Or with pipx: pipx install git+https://github.com/rehan-remade/universal-modder
command -v um
uv tool install git+https://github.com/rehan-remade/universal-modderTrigger the skill with natural requests
You do not need special syntax. Describe the game and the idea in one sentence. The skill is triggered by requests to mod, extend, hack on, reverse engineer or mash up a game. Good starting points are a concrete addition or a feasibility question.
Before building, the agent will usually confirm what done means. For most projects that is a working change in the game plus a 20 to 45 second clip.
- "Add a nuke to Terraria"
- "Make a new civ for Age of Empires"
- "Put Minecraft inside X"
- "Can I mod this game?"
- Give the idea in one sentence, for example: a homing missile launcher and a nuke that craters the world
What you need before you start
The skill is not a one-click install. Expect to set up tools and loaders per game. The Windows PC requirement applies to in-game launch, screenshot and input automation; WSL is supported.
Depending on the route, you may also need a game loader such as tModLoader, SMAPI, BepInEx or UE4SS, decompilers such as ILSpy, Ghidra, genieutils or xEdit, and fal API access and a key for generated sprites, textures, models, sound and video.
- Python with uv or pipx, to install the um CLI
- A Windows PC for in-game launch, screenshots and input (WSL supported)
- A game loader matched to the engine, such as tModLoader, SMAPI, BepInEx or UE4SS
- fal API access and key, only if you generate assets
- Decompilers and tools as the route requires: ILSpy, Ghidra, genieutils or xEdit
Safety: scripts, network and what not to mod
The skill runs scripts and uses the network. Read what it is about to run, and keep saves protected. The skill snapshots save folders with um backup before any modded launch, and recommends a separate lab profile or a pristine copy of a world so scripted tests do not destroy your progress.
Do not use it on online or competitive games with anti-cheat. The skill itself says not to mod the client there, and doing so can get accounts banned. It is also framed around games you own; reverse engineering may breach a licence or the law. Keep game files and decompiled code out of any repository, and run um publish check before sharing a mod.
- Back up saves: um backup create "<saves folder>" --name <game>-saves
- Use a lab profile or a copy of the world for scripted runs
- Keep decompiled code and extracted assets outside the repo
- Never commit game files; run um publish check before sharing
- Skip online or anti-cheat games; offer offline modes or official editors instead
um backup create "<saves folder>" --name <game>-savesTips for getting good results
Start small. The skill builds one item, unit or weapon end to end with placeholder art, proves it appears and works, and only then widens. Ask for that first slice rather than a full game overhaul.
Name the engine if you know it, and let the agent confirm it with um scan. Record your choices in MODLOG.md so a later session can pick up where the last one stopped.
- Give one clear idea and one definition of done
- Let the agent check the engine with um scan before picking a route
- Ask it to show you screenshots it has actually looked at
- Expect manual setup steps for each game
What people use it for
- Adding a homing missile launcher and a tactical nuke to Terraria through the tModLoader route, as in the project described in the case studies
- Creating a new Age of Empires II civilization with 3D-rendered units, while noting that the civ picker is hard-coded in the executable
- Making a recorded proof-of-concept clip of a new enemy or boss for a single-player game you own
- Learning how mod loaders, decompiled code and game data fit together by following the playbook for your engine
- Scoping a mashup idea, such as putting one game's content inside another, using the mashup-mods companion skill
Frequently asked questions
How do I install the mod any game skill?
Download the ZIP from the skill's page on this directory and unzip it into ~/.claude/skills/ for personal use, or into a project's .claude/skills/ folder. In the Claude apps you can instead upload the ZIP under Settings → Capabilities → Skills.
What does the mod-any-game skill require?
It requires Python with uv or pipx to install the um CLI, a Windows PC for in-game launch and automation (WSL is supported), and a game loader such as tModLoader, SMAPI, BepInEx or UE4SS depending on the engine. fal API access and a key are needed only for generated assets, and decompilers such as ILSpy or Ghidra are needed as the route requires.
Is the mod any game skill free?
The skill is published under the MIT licence, as stated on its page. The tools it uses have their own licences and terms, and generated assets go through the fal service, which needs API access and a key.
Can I use it on online games?
No. The skill says not to mod the client of online or competitive games with anti-cheat, and modding them can get accounts banned. It is intended for offline single-player games you own, or for private servers you run yourself.
Is there a one-click install for each game?
No. The skill relies on a CLI tool, external loaders and often manual setup per game, so expect some configuration work before a mod runs.
How is this different from just asking an AI to write mod code?
The skill follows a full workflow: it scans the game, backs up saves, reads the real code and data, builds a small slice, and verifies it in the running game with screenshots. It also keeps a journal and can cut a showcase video, rather than only producing code you then have to test yourself.
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Our verdict
Use this skill if you own an offline single-player PC game and want an idea built, tested in the real game and recorded, and you are comfortable setting up loaders and tools. Pick something else if you want a one-click install, or if the game is online or competitive with anti-cheat, where modding the client is not appropriate.
Download the skill