GameCodex

A game designer AI lens for programmers.

Your AI assistant writes competent game code and gives you zero design judgment. It will implement a jump, a shop, or a crafting system without ever asking whether it should exist, what it should feel like, or which proven design thinking applies. GameCodex fixes exactly that: one MCP tool — lens — that answers as the game designer looking over your shoulder.

you (or your AI): lens { situation: "my jump feels floaty" }

              → Game Feel (Steve Swink): measure input-to-photon latency;
                derive gravity from jump height + time-to-apex; split
                rising/falling gravity; the questions, red flags in code
                terms, and concrete fixes.

Every lens distills an industry-proven philosophy with real provenance — Mark Cerny's Method, MDA, Sid Meier's interesting decisions, Swink's game feel, juice, flow & difficulty (incl. Celeste's assist thinking), George Fan's onboarding rules, Nintendo's kishōtenketsu, core loops, Derek Yu on finishing, Valve-style playtesting, Self-Determination Theory, Sirlin/Schreiber balance, Koster's theory of fun, and BotW-style emergence.

Install

claude mcp add gamecodex -- npx -y gamecodex

Or in any MCP config (claude_desktop_config.json, .cursor/mcp.json, …):

{
  "mcpServers": {
    "gamecodex": { "command": "npx", "args": ["-y", "gamecodex"] }
  }
}

One tool — the whole game

Call	Returns
lens { situation: "players quit at the first boss" }	The matching lenses (here: flow & difficulty, playtesting) — designer questions, red flags, prescriptions — plus matching docs from the knowledge base
lens { lens: "scope" }	One named lens in full
lens { doc: "G106" }	A knowledge-base doc (big ones return a table of contents; add section: "…" for one part)
lens { }	The catalog of all 15 lenses

That's the entire tool surface. No schema bloat, no action routing.

The knowledge base works within the lens

The 957-doc engine library (29 engines — deepest on MonoGame, Godot, Unity, Unreal) is reachable through the same tool: every situation reply ends with the matching docs, and doc/section reads them — section-aware, so 100KB guides never flood your context. The docs also ship as passive MCP resources (gamedev://docs/...). Scope which modules load with GAMEDEV_MODULES (e.g. core,godot-arch).

Monorepo

GameCodex/
├── packages/
│   ├── server/    <- the MCP server (the product) — see its README + SPEC.md
│   └── site/      <- marketing site (stale; predates the lens direction)
└── package.json   <- npm workspaces root

npm install && npm run build && npm test

Links

• npm
• GitHub (canonical)
• Issues
• GitLab mirror

License

MIT