Modder

Modder

The dotclaude-modder plugin lets Claude mod a PC game that you own. It is a Bun and Python port of universal-modder by Rehan, under the MIT license.

Before you begin

1. Install Bun 1.4.2 or later.

2. Install uv for um sprite, um video, and um backup. Without uv, these commands run with the system Python, which then needs Pillow 10 or later and numpy.

3. Install the tools for the parts that you use:

   • ffmpeg for um video and for recording
   • Blender for um render3d, or set BLENDER to its path
   • ComfyUI for um comfy

4. Install the plugin.

   /plugin install dotclaude-modder@dotclaude
   

5. For um fal and the fal MCP server, enter your key from https://fal.ai/dashboard/keys in the fal_key option. Without the option, um fal reads FAL_KEY from the environment.

Warning: Mod only offline and single-player games. A modded game on official online servers, or a bypass of DRM or anti-cheat, can get your account banned.

What it does

Part	What it does
Kill guard	Denies a Bash call that stops processes by name, such as pkill, killall, taskkill /IM, or Stop-Process -Name.
mod-any-game skill	Tells Claude how to do each step of a mod, with the um commands.
um command	Does the work of the skill. The plugin bin/ puts it on the Bash PATH.
fal MCP server	Lets Claude call fal models directly.

The plugin adds no text to the start of a session. Until Claude loads the skill, the plugin costs only the skill listing and the names of the fal MCP tools. Install it only on the machine where you mod games.

The skill

mod-any-game is the only skill. Its SKILL.md has the loop from the idea to a clip, and the rules. Claude reads each step file in references/ only when it gets to that step.

Reference	Use it to
game-recon.md	Find the engine, the anti-cheat, and the route, and write MODDING_PLAN.md.
game-automation.md	Test a mod in the game: screenshots, input, and recordings.
asset-pipeline.md	Make sprites, textures, and models that fit the game.
fal-assets.md	Generate assets with fal models.
mashup-mods.md	Bring content from one game into another.
publish-mod.md	Check a mod before you share it.
share-field-notes.md	Read and write notes for the shared knowledge base.
showcase-video.md	Make a video that shows the mod.
engines/*.md	Read the playbook of the engine that um scan names.

For reverse engineering, mod-any-game refers to the skills in xsyetopz/skills, such as reverse-engineer-binary and decompile-to-matching-c-cpp. The plugin has no agent.

The um command

Group	What it does
um scan	Finds installed games and fingerprints one: engine, runtime, anti-cheat, mod loaders, and routes.
um fal	Generates game assets with fal.
um comfy	Generates images locally with ComfyUI.
um sprite	Cuts out, fits, pixelates, recolors, and packs 2D sprites.
um render3d	Renders a GLB into sprite frames from the camera of a game.
um video	Compiles showcase videos, and trims and muxes clips.
um win	On Windows and WSL: screenshots, recordings with game-only audio, input, and processes.
um backup	Makes and restores snapshots of save folders.
um publish	Checks a mod folder for game files, decompiled code, secrets, and credits.
um kb	Searches, writes, and checks field notes, and opens a pull request.

Run um <group> --help for the commands and options of a group.

Environment variables

Variable	Default	What it sets
UM_HOME	~/.universal-modder	The folder for backups and downloaded tools.
UM_KB	none	A local folder of field notes.
UM_KB_REPO	rehan-remade/universal-modder	The GitHub repository of the field notes.
UM_KB_BRANCH	6715445 (2026-10-05)	The branch or commit of the field notes. The default is a reviewed commit. Set main for the latest notes, or set a commit SHA that you reviewed. With UM_KB_REPO set, the default is main, because the reviewed commit is not in a fork.
UM_NO_UV	none	When set, the Python groups run with the system Python.
BLENDER	none	The path to Blender.
UM_FFMPEG_WIN	none	The path to a Windows ffmpeg that has gfxcapture.

Related pages

• Attributions: the source of the port.
• Install: the other plugins.