Cursor 3 vs DOOM MCP

Cursor 3 is a major version release that transforms the AI coding editor into a full agent coordination platform. The headline feature is a unified workspace: every agent session — whether triggered from mobile, web, Slack, GitHub, Linear, or locally — appears in a single sidebar. You can see all running agents, their current state, and switch between local and cloud execution seamlessly. The release also introduces a marketplace for agent plugins and MCP (Model Context Protocol) servers, enabling a third-party ecosystem of specialized tools that agents can discover and use. The PR and diff interface has been completely redesigned for multi-agent workflows, with visual conflict resolution when multiple agents modify related code. Cursor has been on a remarkable trajectory — from a VS Code fork to the dominant AI IDE to now positioning as an agent orchestration layer. Cursor 3 is the clearest statement yet that the endgame isn't a better text editor; it's a platform where humans and AI agents collaborate on software production at scale.

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.