GPT-6 Astra and Claude Opus 5.5 face off in a MuJoCo sumo match

Jiafei Duan @DJiafeiOriginally posted 2026.09.23

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Is Opus 5.5 better than GPT-6 Astra at Physical Intelligence "literally" ? put GPT-6 Astra and Claude Opus 5.5 in two Unitree G1s in MuJoCo Ring Fence. Every 2 sim seconds: state → LLM → joint targets → act. Goal: force the other out of the ring, and Astra won after 31 second.