DOOM MCP vs GitNexus

Chris Nager built a fully playable DOOM that runs as an MCP (Model Context Protocol) app, rendering inline inside Claude and ChatGPT without a separate browser tab. The architecture uses two MCP tools — create_doom_session for inline-capable hosts and get_doom_launch_url as a browser fallback — combined with cloudflare/doom-wasm for the game runtime and a signed token system that maintains session state across both surfaces. The result is the same session whether you're playing inline or in a tab. The key technical challenge was avoiding iframe and CSP (Content Security Policy) issues. Rather than embedding a browser page inside the MCP iframe, the DOOM canvas runs directly inside the host's iframe — a subtle but critical distinction that resolved a class of rendering and input-handling bugs. The final implementation is intentionally stripped down: no save/load, no persistence adapters, just stable playable DOOM. Beyond the novelty, this project is a concrete demonstration that MCP apps are interactive surfaces, not just tool-calling JSON endpoints. The progressive enhancement pattern — same signed-token foundation serving both inline and browser modes — is a reusable architecture for any game or interactive experience that wants to live inside an AI assistant. Nager open-sourced the implementation and the blog post is a detailed technical breakdown.

GitNexus is a zero-server code intelligence engine that solves one of the core limitations of LLM coding assistants: they rediscover code structure from scratch on every query. Instead, GitNexus precomputes a full knowledge graph of your codebase — every function, dependency, call chain, and execution flow — then exposes it through a Graph RAG agent and native MCP tools for editors like Claude Code, Cursor, and Codex CLI. The architecture is unusual: the entire engine compiles to WebAssembly, meaning it runs both in Node.js and fully client-side in the browser without any server infrastructure. The Graph RAG layer performs multi-hop reasoning over the code graph rather than simple embedding similarity, which means it can answer "what would break if I change this function" rather than just "where is this function defined." MCP tool exposure means AI agents in supporting editors can query the graph natively. The tool gained 837 new GitHub stars today as it caught a second wave of attention after its February launch. It's particularly compelling for monorepos and multi-language projects where file-by-file context injection fails. The PolyForm Noncommercial license makes it free for open-source projects, with commercial licensing available through AkonLabs for teams.