OpenAI Codex
OpenAI's coding agent for terminal, IDE and cloud
- Best for
- Developers with a ChatGPT plan who want an agent to build and fix game code locally or in the cloud
- Makes
- Code changes, tests and reviews in your own repository
- Made by
- OpenAI
- Where you use it
- CLI, macOS, Windows, Linux, Web, iOS
- Engines
- Unity, Unreal Engine
- Pricing
- Free and Go ($8/month) plans get Codex in the ChatGPT desktop app only; Plus ($20/month) adds web, CLI and IDE extension; Pro from $100/month; also usable with an API key at API rates (as of October 2026)
- Free plan
- Yes
- Open source
- Yes (Apache-2.0 (CLI only))
- Export
- Codex works on your own repository, so the code it writes is yours to ship anywhere
- Status
- Available
Codex is OpenAI's AI coding agent. OpenAI's docs describe a CLI that inspects code, edits files and runs the tools on your machine, an IDE extension for VS Code and compatible editors such as Cursor and Windsurf (JetBrains IDEs and Xcode have their own integrations), the ChatGPT desktop app for macOS and Windows with a Linux install guide, a web version and cloud tasks. Only the CLI is open source: the openai/codex repository on GitHub, created in April 2025, uses the Apache-2.0 license, while the ChatGPT apps and Codex cloud are closed. The docs also cover MCP, AGENTS.md project files and skills.
For game developers, Codex is a general agent rather than a game tool. Unity's documentation lists it among the three agents its official plugin supports (Unity 6.0 or later), and the Ultimate Engine CoPilot plugin for Unreal says it can run Codex inside the editor. An unconfirmed Codex Insider article says agents using Codex and Claude Opus wrote about 3,700 commits in two weeks for Pixkrieg, a browser real-time strategy game; it doesn't name the developer.
As of October 2026, OpenAI's pricing page says Codex comes with every ChatGPT plan, but Free and Go ($8 a month) get it only in the desktop app, subject to rollout; Plus ($20 a month) adds the CLI, IDE extension, web and iOS. AIGamer hasn't tested it.
Plans and pricing
| Plan | Price | What you get |
|---|---|---|
| Free | $0 | Desktop app only, subject to rollout |
| Go | $8/month | Desktop app only, subject to rollout |
| Plus | $20/month | Adds web, CLI, IDE extension and iOS, plus cloud features such as automatic code review |
| Pro | From $100/month (tiers at $100, $200 and $500) | Everything in Plus; higher usage |
| Business | $25/user/month, or $20/user/month billed annually (2+ users) | Admin controls such as SAML SSO |
| Enterprise & Edu | Contact sales | |
| API key | API rates | CLI, SDK and IDE extension; not cloud features such as GitHub code review |
From OpenAI Codex's own pricing page, checked 29 October 2026. Prices change; check before you buy.
Limitation: On the Free and Go plans Codex runs only in the ChatGPT desktop app; the CLI and IDE extension start with Plus at $20 a month, per OpenAI's pricing page.
FAQ
Is OpenAI Codex free?
Partly. OpenAI's pricing page says Free and Go plans can use Codex in the ChatGPT desktop app, subject to rollout. The CLI, IDE extension and web version start with Plus at $20 a month, or you can use an API key at API rates.
Can Codex build a game?
It can write game code in any stack. An unconfirmed Codex Insider article says agents using Codex and Claude Opus made about 3,700 commits to the browser strategy game Pixkrieg in two weeks.
Does Codex work with Unity?
Yes. Unity's official plugin supports Codex alongside Claude Code and Grok, and needs Unity 6.0 or later.
Is OpenAI Codex open source?
Only the Codex CLI. The openai/codex repository on GitHub is published under the Apache-2.0 license; the ChatGPT desktop and web apps and the Codex cloud service are not open source.
Sources
Compiled by AIGamer from OpenAI Codex's own pages and the sources below, checked 29 October 2026. We haven't tested OpenAI Codex hands-on.
- OpenAI: Codex pricing
- OpenAI: Codex CLI (docs)
- OpenAI: Codex IDE extension (docs)
- OpenAI: ChatGPT desktop app (docs)
- OpenAI: ChatGPT and Codex docs
- OpenAI: openai/codex (GitHub repository)
- Unity: About Unity's plugin (docs)
- BlueprintsLab: Ultimate Engine CoPilot FAQ (docs)
- Codex Insider: Pixkrieg, a multiplayer browser game with a Rust server
Image: OpenAI
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