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universal-modder

Gives a coding agent skills, a CLI and a shared knowledge base for modding PC games you own

Install as a Claude Code plugin

/plugin marketplace add rehan-remade/universal-modder
/plugin install universal-modder@universal-modder

Copied from the project's docs at github.com/rehan-remade/universal-modder

Why you'd want it

universal-modder packages Agent Skills, three subagents and a Python CLI called um that a coding agent uses to mod a game: um scan finds Steam, Epic and Xbox installs and fingerprints the engine, loaders, anti-cheat and save folders, um backup snapshots saves, and um fal, um sprite and um render3d make and fit art, 3D and audio for the engine. The mod-any-game skill runs a fixed loop of recon, a backed-up lab, reading the real code, building one slice, testing it in the running game and writing a field note. Those field notes live in a knowledge base in the repo that agents search with um kb before starting and add to by pull request.

Best for

  • Modding single-player PC games with an agent
  • Generating sprites and 3D assets for mods
  • Reusing other agents' modding notes

Use it when

You want Claude Code, Codex, Gemini CLI or another agent to work out how a game you own is built and ship a mod for it, with assets and an in-game test.

Skip it if

You play online games with anti-cheat: its own safety notes say injecting into an online client breaks the game's terms and gets accounts banned, and it refuses to do so. It touches game folders, saves, processes and your mouse and keyboard (asking first), asset generation needs a fal API key or a local ComfyUI server, and the repo is about two weeks old with no tagged release.

Editor's note

Outside a plugin install, the README installs the um CLI with uv tool install git+https://github.com/rehan-remade/universal-modder; it also needs Git, Python 3.10+ and ffmpeg.

Related tools

Same category or shared tags.

  1. Spec Kit

    Devtool Standard

    Gives coding agents structured processes for spec-driven builds, bug fixes and idea assessment

    • 141k stars
    • 337 stars/day since creation
    • pushed
    • v1.2.0 on
    • MIT

    Install with uv and create a project

    uv tool install specify-cli
specify init my-project --integration copilot
    Use it when, skip it if, stats for Spec Kit

    Why you'd want it

    The specify CLI installs skills or command files for your coding agent, which you then run in chat: constitution once per project, then specify, plan, tasks, implement and converge for each feature. Optional extensions add a bug-fixing flow (assess, fix, test) and an idea assessment flow that ends in a go, clarify or stop decision, with reports saved as Markdown under .specify/. It has integrations for dozens of agents, including GitHub Copilot, Claude Code, Codex CLI, Cursor, Gemini CLI and Zed, and you can customize it with extensions, presets and workflows.

    Best for

    • Teams that want a spec before code
    • Keeping agent work reviewable step by step
    • Using one process across several coding agents

    Use it when

    You want a coding agent to work from a written specification, plan and task list rather than one prompt, with artifacts you review at each step.

    Skip it if

    Your changes are small enough that a single prompt does the job. The CLI needs Python 3.11+ and uv.

    Stats

    Stars
    141,318
    Last push
    Release
    v1.2.0,
    License
    MIT
    Pricing
    Open source
    Works with
    Claude Code, Cursor, Codex, Gemini CLI, Zed, Linux, macOS, Windows
    Stars per day, since repo creation
    337
    Tier
    Standard, not ranked

    Full stat block for Spec Kit

  2. Rank 5

    Agent Skills (Addy Osmani)

    Devtool

    Adds engineering workflow skills for specs, tests, review and shipping to your coding agent

    • score 64
    • 107k stars
    • 442 stars/day since creation
    • pushed
    • 0.6.13 on
    • MIT

    Install all skills with the skills CLI

    npx skills add addyosmani/agent-skills
    Use it when, skip it if, stats for Agent Skills (Addy Osmani)

    Why you'd want it

    Agent Skills is a pack of SKILL.md workflows covering the path from idea to launch, such as spec-driven development, test-driven development, code review, security hardening and shipping, each ending with evidence requirements like passing tests or build output. It also ships reviewer personas, reference checklists and, in Claude Code, slash commands such as /spec, /plan, /build, /test, /review and /ship. It installs with the skills CLI or as a Claude Code, Codex or Gemini CLI plugin, with setup guides for Cursor, Windsurf, OpenCode and GitHub Copilot.

    Best for

    • Making agents write specs and tests first
    • Shared engineering standards across several agents
    • Structured code review before merge

    Use it when

    Your coding agent skips specs, tests or review and you want step-by-step workflows it follows across a project.

    Skip it if

    Your changes are small one-off edits where a spec, plan and test cycle adds overhead. Installing a single skill with npx leaves out the shared reference checklists.

    Stats

    Stars
    106,751
    Last push
    Release
    0.6.13,
    License
    MIT
    Pricing
    Open source
    Works with
    Claude Code, Cursor, Codex, Gemini CLI, Windsurf
    Stars per day, since repo creation
    442
    New and rising score
    64 of 100

    Full stat block for Agent Skills (Addy Osmani)

  3. Rank 7

    herdr

    Devtool

    Keeps coding agent terminals running in a background server and marks each pane as working, blocked or idle

    • score 59
    • 44.1k stars
    • 219 stars/day since creation
    • pushed
    • v0.9.5 on
    • Apache-2.0

    Install with Homebrew

    brew install herdr
    Use it when, skip it if, stats for herdr

    Why you'd want it

    herdr is a terminal workspace for coding agents, a single Rust binary that runs inside the terminal you already use. Terminals keep running in a background server when you close the client or lose an SSH connection, and after a restart it restores the saved layout and can resume supported agent sessions. Every pane is marked working, blocked or idle, local and saved SSH machines share one window, and agents can drive herdr through its CLI and socket API to spawn panes, prompt each other and wait until another agent is blocked. It runs Claude Code, Codex, Cursor, OpenCode and other agents without wrapping them, with tmux-style prefix keys and mouse control.

    Best for

    • Running many terminal agents side by side
    • Detaching from long agent runs
    • Agents on remote machines over SSH

    Use it when

    You run several CLI coding agents at once, often over SSH, and want to detach, come back and see which one needs an answer.

    Skip it if

    You already have a tmux setup you like and run one agent at a time. Agents can use herdr's socket API to spawn panes and prompt other agents, and after a server or machine restart the original processes are gone, only the layout and supported sessions come back.

    Stats

    Stars
    44,074
    Last push
    Release
    v0.9.5,
    License
    Apache-2.0
    Pricing
    Open source
    Works with
    Claude Code, Codex, Cursor, macOS, Linux, Windows
    Stars per day, since repo creation
    219
    New and rising score
    59 of 100

    Full stat block for herdr

For agents

The same entry, as files an agent can read without scraping this page. 

# read one entry
curl -s https://agenttooldrop.com/tools/universal-modder.md

# list the MCP servers in the catalog
curl -s https://agenttooldrop.com/tools.json \
  | jq -r '.tools[] | select(.category=="mcp-server") | .slug'