Codex Built a Game and Then Played It With Me

Why It Matters

By automating UI interaction and self‑validation, Codex shortens development cycles and enables scalable, AI‑driven testing, reshaping how software is built and verified.

Key Takeaways

• Codex now writes, runs, and plays games autonomously.
• AI can manipulate UI elements across browsers and native Mac apps.
• Integrated build‑test‑play loop eliminates manual verification steps entirely.
• Real‑time cursor control enables automated GUI testing and bug reproduction.
• Developers can delegate end‑to‑end tasks, from coding to validation.

Summary

The video showcases a new Codex update that goes beyond code generation, allowing the AI to operate graphical user interfaces, launch applications, and even play games with a human partner. By writing the code, spinning up a server, and opening the resulting game in a browser, Codex demonstrates a complete build‑test‑play cycle within a single tool.

Key insights include Codex’s ability to read page state, issue keyboard and mouse commands, and interact with native macOS apps such as a Tic‑Tac‑Toe client and Spotify. The AI controls its own cursor, enabling it to verify its output, navigate menus, and perform actions without human intervention, effectively collapsing the traditional development loop.

The presenter highlights concrete examples: a co‑op puzzle game built from scratch, a live game of Tic‑Tac‑Toe where Codex moves the pieces, and the AI queuing music on Spotify. These demos illustrate how Codex can both create and consume its own software, turning verification into an automated step.

Implications are significant for developers and QA teams. Automated UI manipulation opens new possibilities for regression testing, bug reproduction, and continuous integration, while freeing engineers to focus on higher‑level design rather than manual verification. The tool promises faster iteration cycles and broader AI‑assisted development workflows.

Original Description

Codex just shipped an update that closes the loop on AI-assisted development.

In this Short I'm walking through the two features that changed how I think about the tool. First, the in-app browser. I asked Codex to build a small co-op puzzle game and run it locally. It wrote the code, opened the game in its own browser, and then played it with me. Reading the page state, clicking buttons in the UI it just built, moving its character alongside mine.

Same capability outside the browser is called Computer Use. Codex can see your screen, move its own cursor, and operate any Mac app. Native app testing, GUI bug reproduction, any app your code depends on.

The bottleneck in AI-assisted development was never writing the code. It was verifying it. Codex just handled that part.

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