Universal Modder Install Guide

Universal Modder gives an AI coding agent modding instructions, a shared knowledge base, asset tools and the um command-line tool. This Universal Modder tutorial walks through the install route for your agent. This guide covers single-player modding only, using games you own.

The installation steps and requirements come from the project README. Keep that page open when comparing your setup, and browse the Universal Modder GitHub repository for the source code.

Claude Code

In Claude Code, add the project’s plugin marketplace, then install its plugin. These are agent commands:

/plugin marketplace add rehan-remade/universal-modder

/plugin install universal-modder@universal-modder

Codex

Add the marketplace and the plugin with the two commands listed for Codex:

codex plugin marketplace add rehan-remade/universal-modder

codex plugin add universal-modder@universal-modder

Gemini CLI

Install the repository as a Gemini CLI extension:

gemini extensions install https://github.com/rehan-remade/universal-modder

VS Code / Copilot

Enable chat.plugins.enabled. Open Chat: Install Plugin From Source and enter the repository URL. This is a settings-and-command-palette route; the README does not give a shell install command for it.

Cursor

Use Cursor Marketplace, or clone the repository. Cursor reads its AGENTS.md instructions and .cursor/mcp.json configuration. The README does not give a more detailed Marketplace walkthrough.

git clone https://github.com/rehan-remade/universal-modder

OpenCode

Clone the repository, then start OpenCode inside the clone. Its opencode.json connects the skills and fal MCP server.

git clone https://github.com/rehan-remade/universal-modder

opencode

Skills only

For an agent that accepts the Agent Skills format, use the README’s skills-only command:

npx skills add https://github.com/rehan-remade/universal-modder

This route is labelled “Skills only”; use the CLI section below when you need the tools separately.

Anything else

Clone the project and start your coding agent inside that folder:

git clone https://github.com/rehan-remade/universal-modder

Inside a clone, .agents/skills serves Codex, Gemini CLI, Copilot, Cursor and OpenCode; .claude/skills serves Claude Code. Both contain copies of the project’s skills. AGENTS.md supplies instructions, with CLAUDE.md and GEMINI.md pointing to it.

Install the um CLI

The README says plugin installations and clones place um on PATH. For other setups, it provides this command, reproduced including its comment:

uv tool install git+https://github.com/rehan-remade/universal-modder     # or: pipx install git+...

The abbreviated pipx text in the comment is the README’s wording, not a complete alternative command. Use the complete uv command shown here.

Asset setup: fal or local ComfyUI

Get an API key from fal’s key dashboard. The README uses this environment-variable example for the fal MCP server and um fal:

export FAL_KEY=...

Replace the placeholder with your own key. This is the README’s shell syntax; it does not document a separate Windows shell equivalent.

For images without a fal key, um comfy uses a local ComfyUI server. The README lists status checks, image generation and API-exported workflows; it does not provide a full local server installation guide. See our fal key guide for the documented scope.

Other requirements

Git, Python 3.10+ and ffmpeg are required by the README.
uv is recommended.
Blender is needed when rendering 3D models into sprites.
The README describes driving Windows games natively or from WSL. It does not provide a complete operating-system compatibility matrix.

Before modifying saves, have the agent back them up. Start with a small change and check it in the running game. The project’s mod-any-game skill begins with existing field notes and game reconnaissance, then builds and verifies one working slice.

For a cross-game project, read how to merge games with AI before choosing the implementation.

Your first prompt

The following are the README’s “Try it” examples, each a short source quotation. Choose one that matches a game you own. They describe a goal, not a promise that every installation will work.

Mod Terraria: add a homing missile launcher and a tactical nuke that craters the world. Make the sprites with fal.

Make a new civilization for Age of Empires II with a unique unit rendered from 3D.

Put real Minecraft inside GTA V story mode. Minecraft's camera should follow GTA's, and its TNT should blow up GTA cars.

Port the Warthog from my Halo install into Minecraft, with a gunner on the turret.

What engine is C:\Games\Foo, and has anyone modded it before?

Source: README: Try it. Ask the agent to identify your installed version and back up saves before making changes.

Something went wrong?

Read Universal Modder troubleshooting for exact reported errors and maintainer replies. The Windows / WSL checklist separates general requirements from example-specific C++ tools. Once setup works, choose a small goal from the prompt library or browse game reports.

Frequently asked questions

Which agents does Universal Modder document?

The README provides install routes for Claude Code, Codex, Gemini CLI, VS Code / Copilot, Cursor and OpenCode. It also lists Skills only and Anything else routes for other agents.

Is a fal API key required for images?

No. For images without a fal key, um comfy connects to a local ComfyUI server. A fal key powers the fal MCP server and um fal.

What other tools do I need to install?

The README requires Git, Python 3.10+ and ffmpeg, and recommends uv. Blender is needed for rendering 3D models into sprites. Plugin installs and clones put the um CLI on PATH; other setups have a separate CLI install command.

Can Universal Modder drive Windows games from WSL?

The README describes driving Windows games either natively or from WSL. It does not provide a complete operating-system compatibility matrix.

Where is the source code, and what is its license?

The source code is in the rehan-remade/universal-modder repository on GitHub. The project is open source under the MIT license.