Universal Modder.
Make something unexpected.

Universal Modder is an open-source collection of skills, command-line tools and game-specific field notes for AI coding agents. It gives an agent a process for investigating an installed PC game, choosing a modding route, building a change, and checking the result in the running game.

You run it with a coding agent on your computer. The project includes integrations for Claude Code, Codex, Gemini CLI, Cursor, VS Code / GitHub Copilot, and OpenCode. Its Python command-line tool is called um. The official repository is the source for installation instructions and project updates.

The toolkit can help with code changes, sprites, other assets, game inspection and packaging. What works depends on the particular game, its version, the available loader and your local setup. A demonstration of one game does not establish compatibility with another release of that game.

New to the project? Read the installation guide. It separates the agent integration from the um command so you can verify both before touching a game.

Already installed? Follow the first-mod workflow. It starts with a small, reversible change and a test you can describe before you generate any code.

Trying to work out the budget? The requirements and costs guide explains which pieces come from the project and which depend on your agent, asset service or hardware.

Looking for a specific game? Use the game examples index. It links to the actual upstream examples and distinguishes recorded tests from broader engine guidance.

Stuck partway through? Open troubleshooting and identify the failing layer before reinstalling everything.

Choose a game you own and can run locally. Give the agent its exact path and version, ask it to inspect the setup, then read its proposed plan. Keep the first change narrow enough that you can tell whether it worked: one item label, one configurable value, or one original asset in an established modding route.

Before making changes, locate and back up the relevant saves. Keep the original files and the working mod separate. Ask the agent to explain what it will edit and how you will undo the change. Once the mod builds, launch a disposable test save and check the feature yourself.

The upstream workflow also includes recording, packaging and writing a field note. Those steps become useful after the mod works. You do not need to turn your first experiment into a public release.

Is Universal Modder free?

The project is released under the MIT license. That does not include paid access to an AI coding agent, game purchases or an asset-generation service. Check those separately before you start.

Is this the official website?

No. This is an independent guide. The project is maintained at rehan-remade/universal-modder on GitHub. We link to upstream instructions and examples rather than hosting installers or asking for your keys.

Does it work with every game?

The name describes the project's broad ambition. A usable route still depends on your game and environment. Read a relevant field note, compare versions, and establish a small working test before investing in a larger mod.

Do I need to know how to code?

An agent can write code, but you still need to install tools, read a plan, recognize errors and test the result. If you are new to this, use a game with an established mod loader and keep the first task small. The first-mod guide includes a prompt you can adapt.

Can I use it for online games?

The project's safety rules prohibit anti-cheat bypasses and cheating against other players. Follow the game's rules and the documented modding route. For a first experiment, an offline test environment is easier to control.