Third-party repos we don't own or vouch for. AI-generated use cases can be wrong: review everything and run at your own risk.
Authorization notice. This tool is dual-use. Only use it on software, sites and systems you own or have explicit permission to test, and follow the relevant licenses and terms of service.
WhoModder who finished a game mod and wants to help the next person avoid the same dead ends
The problemHard-won details like which version worked or why a crash happened get lost, and others redo the same reverse engineering.
The outcomeA checked field note in the shared knowledge base with versions, route, verification and gotchas.
Steps
Run um kb new --game "Hades II" --title "A new boon god" --from-scan hades --agent "Codex (gpt-6)", using your own game, title and agent.
Fill in the note honestly, then validate it with um kb check knowledge/games/hades-ii/a-new-boon-god.md.
After your human says OK, open the PR with um kb pr knowledge/games/hades-ii/a-new-boon-god.md --yes.
Prompt for your agent
Use universal-modder's share-field-notes skill to write a field note for the <game> mod we just finished. Include versions, route, verification and gotchas, run the check, and wait for my approval before opening the pull request.
Caveat. Notes must not include game files or decompiled dumps, and must state an honest status and verification; the repo is alpha.
WhoTerraria player who wants a homing missile launcher and a custom boss but has never written a mod
The problemWriting a mod means learning the game's engine, code layout and asset formats before anything shows up on screen.
The outcomeA working mod with generated sprites, tested in the real game, plus a recorded showcase clip.
Steps
Install the plugin for your agent, for example /plugin marketplace add rehan-remade/universal-modder then /plugin install universal-modder@universal-modder in Claude Code.
Store your fal key with um fal key set and start your agent with FAL_KEY set.
Tell the agent what to add, for example a homing missile launcher and a tactical nuke for Terraria, with sprites made by fal.
Let it run the mod-any-game loop: recon, read the code, build one slice, generate assets, verify in game.
Review the result and the showcase video it cuts.
Prompt for your agent
Use universal-modder to mod <game name> installed at <path to game folder>: add <new item or boss>. Generate the art with fal, test it in the running game, and tell me which route and engine you used.
Caveat. Targets games you own, single-player or offline only. The README says it refuses to bypass anti-cheat or write multiplayer cheats.
Record the game window with only game audio, pick the best moments and edit a styled clip.
Intermediate
1 hour
From the README
Any agent
WhoModder who finished a mod and needs a trailer for Discord or social posts
The problemScreen recording picks up desktop noise, and editing highlights by hand takes longer than building the mod.
The outcomeA short, cut video of the mod running in the real game with clean audio.
Steps
Have a mod that already runs in the game.
Ask the agent to use the showcase-video skill to record the window with only the game's audio.
Let it pick moments and cut the clip from an edit decision list.
Check the result against the actual gameplay before posting.
Prompt for your agent
Use universal-modder's showcase-video skill to record <game> running my mod <mod name>. Pick the best moments and cut a short video with game audio only, and tell me the file path.
Caveat. Needs ffmpeg and a game that can run in a window; GPU-heavy games may need the screenshot and windowed-mode steps from game-automation.
Point the agent at a game folder to get the engine, version, modding route and any existing field notes.
Beginner
30 minutes
From the README
Any agent
WhoHobbyist who just bought an older PC game and wants to know whether modding it is realistic
The problemYou cannot tell what engine a game uses or whether anyone has already worked out how to mod it.
The outcomeA MODDING_PLAN.md with engine, version, managed or native code, anti-cheat status, save folders and the best known route.
Steps
Install the plugin or the skills with npx skills add https://github.com/rehan-remade/universal-modder.
Search prior art first with um kb search "grand theft auto", swapping in your game's name.
Ask the agent to run the game-recon skill on your install folder.
Read the generated MODDING_PLAN.md before deciding to build anything.
Prompt for your agent
Use universal-modder's game-recon skill on <path to game folder>. Tell me the engine, whether it is managed or native, any anti-cheat, and whether the knowledge base already has notes on it. Write the result to MODDING_PLAN.md.
Caveat. Recon output is the agent's reading of files on disk; confirm anti-cheat status yourself before launching an online game with any mod.
WhoFan with a mashup idea, such as a Warthog from Halo driving around Minecraft
The problemCombining two games means extracting assets from one and wiring them into the other's engine, a project few people finish alone.
The outcomeA playable mashup mod where content from game A runs inside game B, with a showcase video.
Steps
Install the plugin and set up your fal key for any new art or audio.
Describe the mashup to the agent, naming both games and the one thing to bring over first.
Let the mashup-mods skill pick an approach: content port, passthrough mod, or reimplementation.
Build and verify one working slice in the running game before adding more.
Prompt for your agent
Use universal-modder's mashup-mods skill to bring <thing from game A> into <game B> installed at <path>. Start with one working slice and show me a screenshot from the running game as proof.
Caveat. Mashups reuse other studios' assets; the README's contribution rules forbid sharing game files or decompiled dumps, so publish only your own code and generated art.
Generate engine-ready sprites, 3D models, sound effects and music for a mod instead of drawing them by hand.
Intermediate
1 hour
From the README
Any agent
WhoSolo modder who can code a little but cannot draw or make audio
The problemMod ideas stall because every new unit, item or sound needs original art that fits the game's format.
The outcomeA set of transparent sprites, rendered 3D headings or audio files sized and named to match the target game.
Steps
Create a fal API key and store it with um fal key set.
Start your agent with FAL_KEY set, for example export FAL_KEY="$(secret-tool lookup service fal.ai key api)" on Linux.
Ask the fal-assets skill for the asset, such as a unit rendered from 3D into 8 or 16 headings.
Use the asset-pipeline skill to cut out, fit and pack frames into the sheet size the game expects.
Prompt for your agent
Use universal-modder's fal-assets and asset-pipeline skills to make <asset description> for <game>. Output engine-ready frames at <size> and show me the sheet.
Caveat. fal is a paid service billed to your key, and 3D to sprite rendering needs Blender installed.
Move a mod from an old Minecraft version or loader to a new one without behavior drifting.
Advanced
A few hours to days
From the README
Claude Code
Codex
Cursor
Gemini CLI
Any agent
WhoMinecraft mod maintainer whose favorite old mod stopped working after an update
The problemA manual port loses behavior along the way and nobody notices until players report bugs.
The outcomeA ported mod built unit by unit from one pinned source, with audits and status docs you can resume.
Steps
Install the plugin and open your agent in the project.
Pin the source mod version and let the agent decompile it privately.
Ask the port-a-mod skill to extract data by script and port unit by unit with tests.
Review the layer audits and the status docs before releasing.
Prompt for your agent
Use universal-modder's port-a-mod skill to port <mod name> from <old version and loader> to <new version and loader>. Pin one source, port unit by unit with tests, and keep a resumable status doc.
Caveat. Check the original mod's license before porting and publishing; the README's example mapping covers Forge 1.7.10 to Fabric 1.20.1 only.
Have the agent decode a proprietary asset or save format and prove it with a round trip.
Advanced
A few hours
From the README
Any agent
WhoTinkerer who wants to swap textures or data in an older game but cannot open its files
The problemProprietary archives and formats have no documentation, so editing assets is impossible without reading the binary.
The outcomeA working reader and writer for the format, proven by unpacking and repacking a file and getting the same game behavior.
Steps
Install the plugin and point the agent at the game folder and the file type.
Ask the reverse-engineering skill to analyze the format with its tools such as ILSpy, Ghidra or Cheat Engine as appropriate.
Have it write a script that reads the format and a writer that rebuilds it.
Verify with a round trip: unpack, repack, and load the result in the game.
Prompt for your agent
Use universal-modder's reverse-engineering skill on the <file type> files in <path to game>. Work out the format, write a reader and writer, and prove it with a round trip that still loads in the game.
Caveat. Only for games you own and local single-player use. Do not redistribute extracted game assets, and do not use it to defeat anti-cheat or cheat other players.
Who it is forFor gamers and hobbyist modders who own PC games and have a coding agent, and want to add custom content or cross-game mashups without learning each engine from scratch.
Why it is hotabout +444 stars a day since launch, 8.4k total, launched 19 days ago, talked about in 2 AI sources we track
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