Two Games in One Frame: How Passthrough Mashups Work

Passthrough mods ("mashups") run two modified games in parallel and synchronize entities, collisions, and frames via local IPC, while the mashup-mods skill from the universal-modder repository turned this methodology into a reproducible template for AI agents.

Compiled by Sergey KostenchukPublished 2026-10-05Updated 2026-10-05

2026-10-05 Coding Anthropic

🎮 Two Games in One Frame: How Passthrough Mashups Work

Two modified games run in parallel and synchronize entities, collisions, and frames via local IPC — WebSocket, shared memory, UDP. In the Minecraft × GTA V example, a Minecraft frame is embedded into a GTA frame using the depth buffer, while TNT and arrows become explosions and bullets. A video of Minecraft inside Elden Ring has gathered 22.8 million views.

🌍 The mashup-mods skill condensed five "game within a game" patterns into a single template: AI agents use it to combine closed-source engines without source code.

👤 The methodology is open: the universal-modder repository (MIT) can be installed as a plugin in Claude Code, Codex, or via npx skills add. It includes a code example and an honest caveat: passthrough is a trick for views and prototypes, not a full integration.

Source 1: https://github.com/rehan-remade/universal-modder/blob/main/skills/mashup-mods/SKILL.md Source 2: https://x.com/TobynJacobs/status/2104884843297599594

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