Free guide · Oct 1, 2026
Mod almost any PC game with Claude Code
Install Universal Modder in Claude Code, set up your fal.ai key, and build your first single-player mod step by step.
The short version
universal-modder is a free, open source set of skills, tools and notes that turns Claude Code (or Codex, Cursor, Gemini CLI and others) into a game modder. You describe the mod. The agent finds the game, works out the engine, reads the real code, builds the mod, makes the art and sound with fal, tests it in the running game and records a clip.
•What you need: Claude Code, a PC game you own, Python 3.10 or newer and ffmpeg. A fal API key only if you want generated art, 3D or sound.
•What you get: a working single-player mod, plus a write-up of how it was done.
•How to start: install the plugin, ask it to look at one game before changing anything, back up your saves, then ask for one small mod.
What's in the full guide
- 01What it can mod
- 02The three mods it ships with
- 03The rules it follows
- 04Step 1: Install it in Claude Code
- 05Step 2: Add a fal key (only for art and sound)
- 06Step 3: Start with a question, not a mod
- 07Step 4: Back up before anything touches the game
- 08Step 5: Ask for one small mod
- 09Honest notes before you start
- 10Where to go next