GPT-6 Astra Builds a Browser GTA-Style Game in 55 Minutes With One Agent as Fable 5.1 Takes 6 Hours 15 Minutes

OpenAI's GPT-6 Astra, running in Codex as Astra 6, built a playable browser open-world driving game in 55 minutes of active work with a single agent, while Anthropic's Claude Fable 5.1 spent about 6 hours 15 minutes and used 32 implementer and reviewer agents on the same one-shot prompt. The comparison comes from a documented experiment by Nitzan, who published three playable results and the original brief rather than a vendor leaderboard.