DOOM MCP vs Google Scion

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.

Google Scion is an open-source "hypervisor for agents" — a runtime that manages groups of AI agents in isolated containers, each with its own identity, credentials, git worktree, and toolset. Think of it as Kubernetes for agent teams: you declare your agent topology, Scion provisions the sandboxes, and agents can collaborate through structured channels without sharing file system or credential state. The isolation-over-constraints philosophy is Scion's core bet: rather than trying to constrain what a single powerful agent can do, give each agent a minimal, scoped environment where the blast radius of any failure or misbehavior is bounded. Harness adapters allow integration with Claude Code, Gemini CLI, and other existing agent runtimes — Scion acts as the orchestration layer above any underlying agent technology. For teams building multi-agent systems at scale, the credential isolation alone is a major feature — no more worrying about one agent leaking API keys to another. The Docker/Kubernetes support means it drops into existing infrastructure. Scion represents Google's opinionated answer to the question every AI platform team is grappling with: how do you run multiple AI agents safely in production without building a custom isolation layer from scratch?