Swap models, I Put ChatGPT in Claude Code and Claude in Codex

One run per game, with nothing fixed afterwards. The opinions are my own. Play the games each model built in its own coding agent, free in your browser: Sunspur Kart (GPT-6 Astra): https://devarf.dev/play/sunspur-kart/ Aster Circuit (GPT-6 Sol): https://devarf.dev/play/aster-circuit/ Vroomvale (Fable 5.1): https://devarf.dev/play/vroomvale/ Pinwheel Prix (Opus 5.5): https://devarf.dev/play/pinwheel-prix/ Sparkplug GP (Opus 5): https://devarf.dev/play/sparkplug-gp/ Claude Model in Claude code Comet Karts (Fable 5.1 1M): https://devarf.dev/play/comet-karts/ Pocket Rocket Rally (Opus 1M): https://devarf.dev/play/pocket-rocket-rally/ GPT in Claude code Cloudberry Grand Prix (GPT-6 Sol): https://devarf.dev/play/cloudberry-grand-prix/ Sunspill Rally (GPT-6 Astra): https://devarf.dev/play/sunspill-rally/ More games built with AI: https://devarf.dev Chapters: 0:00 Model or coding agent? 1:02 How the swap worked 1:44 GPT-6 Astra: Sunspur Kart and Sunspill Rally 2:45 GPT-6 Sol: Aster Circuit and Cloudberry Grand Prix 3:33 Fable 5.1: Vroomvale and Comet Karts 4:55 Opus 5.5: Pinwheel Prix and Pocket Rocket Rally 6:09 Opus 5: Sparkplug GP 6:34 What stayed with the model 7:58 Time and cost 9:26 What shaped these games? How the games were made: Every prompt's first line was "Create a new folder, then build a 3D racing kart game. Do your own research." Under it, all nine got the same list of rules. What each build ran on: the model as its log records it, the coding agent and version, and the day the build started (UTC). Every log records max effort. Sunspur Kart: gpt-6-astra, Codex 0.153.4, 7 Sep 2026 Sunspill Rally: gpt-6-astra, Claude Code 2.1.283 (terminal), 28 Sep 2026 Aster Circuit: gpt-6-sol, Codex 0.155.0-alpha.16, 22 Sep 2026 Cloudberry Grand Prix: gpt-6-sol, Claude Code 2.1.283 (terminal), 27 Sep 2026 Vroomvale: claude-fable-5-1, Claude Code 2.1.266, 11 Sep 2026 Comet Karts: claude-fable-5-1-1m, Codex 0.158.0-alpha.2.1, 27 Sep 2026 Pinwheel Prix: claude-opus-5-5, Claude Code 2.1.280, 22 Sep 2026 Pocket Rocket Rally: claude-opus-1m (claude-opus-5-5[1m]), Codex 0.158.0-alpha.2.1, 27 to 28 Sep 2026 Sparkplug GP: claude-opus-5, Claude Code 2.1.266, 11 Sep 2026 So each pair differs in more than the coding agent: the bridge, the app version and the date changed too. Nothing here isolates the model or the coding agent. List prices are OpenAI's and Anthropic's published API prices, read 22 to 26 September 2026.