Home › Universal Modder Tutorial

Universal Modder Tutorial

Updated 2026-10-13

This tutorial follows the workflow the toolkit itself teaches the agent: research first, back up, build one small working slice, then test in the real game. It assumes you have already installed Universal Modder.

Quick answer

Start with a single-player game you own; published guides use Terraria as the example.
Ask for a plan before any file is changed.
Build one item, enemy or visual change first, then expand.
Run um publish check before sharing anything.

The loop, step by step

Scan your library
um scan --list lists detected games; um scan "Terraria" fingerprints one. It reports the engine and version, .NET or native, anti-cheat, loaders and save folders, and ranks modding routes. AI Frontier Post says it finds Steam, Epic and Xbox installs.
Search the field notes
um kb search "Terraria" checks whether another agent has already modded this game and what worked.
Ask for a plan, not a mod
Have the agent inspect the game and report version, engine, modding route, save location and anti-cheat concerns without changing files. The chosen route is written to MODDING_PLAN.md.
Set up a safe lab
um backup snapshots, diffs and restores save folders. Run um backup --help for the exact syntax, and use a separate test profile or world where you can.
Let the agent read the real code
Depending on the engine it uses tools such as ILSpy, Cpp2IL, Vineflower, Ghidra or IDA, Cheat Engine, Frida or RenderDoc. You may need to install the ones your game requires.
Build one working slice
One item, one enemy or one visual change, loaded and working in game, before anything bigger.
Generate assets
um fal creates sprites, textures, 3D models, sound and music. um sprite cuts, fits and packs them into sheets; um render3d turns GLB models into sprite frames.
Verify in the running game
um win launches the game, takes screenshots, records and sends input. Check for crashes, wrong sprite dimensions, broken animations and save problems. Reviewers call this the hardest step.
Record and package
um video compile cuts a showcase clip. um publish check blocks game files, decompiled code and leaked keys from the package.
Write a field note
um kb new drafts a note about what worked, um kb check validates it, and um kb pr opens a pull request once you approve.

Example missions

These are the kinds of prompts the README and published guides use:

Terraria: add a homing missile launcher and a tactical nuke.
Age of Empires II: add a new civilization with a unique unit rendered from 3D.
Run Minecraft inside GTA V story mode, with a shared camera and TNT that triggers explosions.
Recon only: “What engine is C:\Games\Foo, and has anyone modded it before?”

If you are new, start with the recon prompt and a one-item mod. The cross-game mashups are the showcase end of the scale.

um command cheat sheet

Command	Purpose
`um scan`	Find installs and fingerprint games
`um kb`	Knowledge base: search, show, new, check, index, sync, pr
`um backup`	Snapshot, diff and restore save folders
`um fal`	sprite, image, edit, rmbg, pixelate, upscale, texture, pbr, model3d, rig, sfx, music, voice, video, run, search, schema, price
`um comfy`	Local ComfyUI: status, image, run
`um sprite`	cutout, fit, pixelate, palette, sheet, slice, frames, team-mask, seamless, preview
`um render3d`	Render GLB models to sprite frames
`um win`	shot, record, drive, ps, kill, launch, reg
`um video`	contact, compile, mux, beats, first-frame
`um publish check`	Block game files, decompiled code and leaked keys

Subcommand names are from the README. Run any command with --help for current flags.

FAQ

What is the best first game to try?

The project does not name one. Published guides use Terraria with tModLoader, which is also the README’s first showcase.

How long does a mod take?

Not published. It depends on the game, the agent and how much asset generation is involved.

The agent wants to control my mouse and keyboard. Is that expected?

Yes, for in-game testing, and the rules say it must ask first. It should also ask before installing a loader into a game folder or publishing.

Unofficial, independent guide. Not affiliated with the Universal Modder project, its maintainers (rehan-remade), fal, Anthropic or any game publisher. The official source is github.com/rehan-remade/universal-modder. We do not host game files, mods or decompiled code. Only mod games you own.