Moonlight & Mayhem: A Raccoon Heist Built by Codex with GPT-5.6 Sol Ultra

Simon Willison previously wrote about using Claude Fable 5 to build a raccoon-heist game from a premise generated by GPT-3 and DALL-E four years earlier. He then posed the same prompt to Codex Desktop running GPT-5.6 Sol Ultra, which aggressively uses sub-agents. Codex produced a better game called Moonlight & Mayhem, available on GitHub with textures and prompts generated using gpt-image-2. The game puts you in a museum, rescuing two raccoon crewmates to stack on top of each other and steal the golden sardine. However, the one-shot version had a bug where each raccoon had an enlarged eyeball sphere floating over their head; Codex failed to spot it despite reviewing screenshots. Willison fixed it by asking why the raccoons have huge black spheres and then saying 'Fix it'. He shared the full Codex transcript in the repository, noting a wish that Claude Code had the same 'copy as Markdown' feature. Codex spent 52 minutes on the project, and the session's AgentsView cost estimate is shown for full API pricing versus the monthly subscription.