Open-source Buddy app runs Codex CLI on Android, builds and installs a game from one sentence
3amae404 · reddit · 2026-10-26
An open-source Android app called Buddy (Apache 2.0) runs the real Codex CLI inside a small Linux environment on your phone — no PC, adb, or root — signed in with your ChatGPT plan.
In the demo, one sentence ("build and install a Pac-Man style maze game with ghosts and touch controls") had Codex write a plain Java game, build a signed APK on-device without Gradle, self-initiate a script verifying every pellet was reachable, and request approval before installing — all in about 2.5 minutes.
Codex also gets screen-viewing and tapping tools so it can operate apps to test its builds. Lessons learned: single-screen, no-library projects build reliably on phones, and letting the model see the screen catches bugs that compile fine. Also works with Claude Code, OpenCode, Antigravity and Grok.
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