What they did
u/abhi3188 used Claude Code to build a sailing simulator. By the poster's account Claude Code wrote nearly all of it: the boat physics, the wind model, the 3D water and coastline, and the harness that lets language models steer a boat. The poster's part was deciding what to build next and checking the results. In a race, every five seconds each model receives 23 raw numbers describing the world, such as heading, speed, wind and the position of the next mark, and replies with helm and sail settings. The models get no sailing advice, and the sim pauses while a model thinks so slow models are not penalised.
How it went
The sim ran and the poster posted a video of a race between Opus, GPT-6 Astra, Gemini 4 Argon and qwen3.5-9b. Argon won, and at $0.78 per run it cost about a fifth of Astra's $3.58. Opus did poorly, and commenters joked that the Qwen model headed for the beach instead of the course. The post drew 460 upvotes and several requests for the code, which the post does not link.
Worth knowing
The build is the agent work here; the race is a single informal run, not a benchmark, and the poster gives no build time or Claude Code cost. Commenters suggested Argon's edge may come from Google training it for spatial tasks in Maps and Earth. Every model had an unlimited budget per race, so the per-run costs reflect how much each one chose to think.