🕹️ Agents Plugins

The CS Modding marketplace (csmodding) of agent plugins for Claude Code and OpenAI Codex CLI.

Give your coding agent eyes and hands inside a running game: its HTML UI, and its C#/ECS
internals.
Generic tooling, developed and verified against Cities: Skylines II.

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Plugins · Install · Development

Plugins

Plugin	Give your agent…	Runs on	Docs
🔬 unity-devtools	A live line into a Unity Mono dev build over the Mono Soft Debugger: reflect types, evaluate C# expressions, read & write ECS state. No code injection. Plus a driving skill.	.NET 10 SDK (Windows)	README · Tools reference · NuGet
🖼️ coherent-gameface	Eyes and hands in any Coherent Gameface (Cohtml) game UI over CDP: evaluate JS, screenshot, drive the DOM, console, JS breakpoints. Plus an engine skill and a driving skill.	Node 22.4+	README · Why · Tools reference · npm
📚 cs2-modding (work in progress)	How Cities: Skylines II is built and how a mod changes it: the game's architecture, the modding techniques and the game mechanics behind them, every claim deep-verified against multiple sources, including the decompile and the live game. Knowledge only — skills and references, no MCP server.	N/A	Sources

The two toolkit plugins are generic: they target any game or application embedding the
technology, with Cities: Skylines II as the reference target where everything is field-verified.
cs2-modding is the deliberate exception, and is about that game throughout.

[!IMPORTANT]
Coherent Labs published their own Gameface MCP — which should you use? Theirs is built around
a Player.exe from a licensed Gameface SDK; this one attaches to a game that is already running.
Read the full comparison →

[!TIP]
Not using Claude Code or Codex CLI? The Gameface MCP server is also published on npm as
@csmodding/gameface-devtools-mcp
and works with any MCP client (Cursor, Gemini CLI, VS Code, …).

Install

Add the marketplace once, then install the plugin(s) you want. Each plugin that carries an MCP
server autoloads it from a committed artifact: no installation step, works offline, version-locked
to the plugin. cs2-modding carries none and is skills only.

Claude Code

/plugin marketplace add CitiesSkylinesModding/agents-plugins
/plugin install coherent-gameface@csmodding
/plugin install unity-devtools@csmodding
/plugin install cs2-modding@csmodding

Or from your terminal, claude plugin marketplace add … / claude plugin install … with the same
arguments.

Codex CLI

codex plugin marketplace add CitiesSkylinesModding/agents-plugins
codex plugin add coherent-gameface@csmodding
codex plugin add unity-devtools@csmodding
codex plugin add cs2-modding@csmodding

Then run /mcp to confirm the servers connected. Each plugin's README covers its requirements,
configuration and troubleshooting.

[!NOTE]
cs2-modding is still being written: not all of its references are published yet, some will be
partly rewritten, and it ships no README so far. What is there is safe to use and already
useful — install it if you want it now, and expect it to grow.

Development

Uses mise + bun (never npx). The repository is a marketplace: plugin sources live under
plugins/<name>/, and everything a plugin ships lives inside its directory. The root is a bun
workspace carrying the lint/format tooling (oxlint, oxfmt) and the lefthook git hooks; the
Gameface MCP server is the plugins/coherent-gameface/mcp/ workspace package, and the Unity MCP
server is a .NET solution (agents-plugins.slnx).

bun install         # install all workspace deps (also installs the git hooks)
mise check          # verify (read-only): type-check, lint, format
mise fix            # auto-fix lint + format in place
mise build          # rebuild every shipped artifact (commit the results)

Run mise tasks for the full list, and see AGENTS.md (plus each plugin's own
AGENTS.md) for the architecture notes.