A knowledge package for writing Cities: Skylines II game modifications, or mods. It covers the game's architecture, modding methods, and mechanics, with claims checked against the game's decompiled code.

Planning and writing Cities: Skylines II code mods for Claude Code or Codex CLI.

It gives the coding agent verified background needed to modify this specific game.

cs2-modding — Plugin by CitiesSkylinesModding

Install

Getting it into your agent

One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.

Claude Code

/plugin marketplace add CitiesSkylinesModding/agents-plugins

agentmods

npx agentmods add plugins/citiesskylinesmodding/agents-plugins/cs2-modding

Clone the repo

git clone --depth 1 https://github.com/CitiesSkylinesModding/agents-plugins

Made for: Claude Code.

Per session not measured What this adds to a session before it is invoked.

When invoked not measured Not applicable: nothing here is loaded into a session.

Security scan A 0 findings. Scan, not verified.

Origin original No closer match found in the catalogue.

Security

Grade A, and why

cs2-modding scanned grade A with 0 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured yesterday.

A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.

Nothing flagged

None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.

plugins/cs2-modding/.claude-plugin/plugin.json · 21 lines

What it actually says

{
  "name": "cs2-modding",
  "version": "1.0.0",
  "description": "Teach your coding agent to write Cities: Skylines II code mods (Claude Code, Codex CLI): the game's architecture, the modding techniques and the game mechanics behind them, every claim verified against the decompiled game. Knowledge only, no MCP server.",
  "author": {
    "name": "Morgan Touverey Quilling"
  },
  "homepage": "https://github.com/CitiesSkylinesModding/agents-plugins",
  "repository": "https://github.com/CitiesSkylinesModding/agents-plugins",
  "license": "MIT",
  "keywords": [
    "cities-skylines-2",
    "cities-skylines",
    "game-modding",
    "unity",
    "unity-entities",
    "ecs",
    "skills"
  ]
}

Changes

What this file has done since we first saw it

Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.

yesterday First seen · 21 lines scan A 62ed00f1a237

Subscribe to this mod's changes

cs2-modding is a plugin published in the GitHub repository CitiesSkylinesModding/agents-plugins (5 stars, last pushed 2d ago), licensed MIT. Its token cost is not measured: this kind of file is read by the harness, not the model. A static security scan graded it A with 0 findings. No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-31.

Learning and teaching Planning Writing and docs chrome-devtools-protocol cities-skylines-2 claude-code claude-code-plugins claude-code-plugins-marketplace claude-plugins

cs2-modding

Getting it into your agent

Grade A, and why

Nothing flagged

What it actually says

What this file has done since we first saw it

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