Meet GPT-5.6

Watch GPT-5.6 build a playable, celestial-themed card game in Codex from a short, open-ended prompt. In this demo, GPT-5.6 designs the core mechanics, generates custom artwork, adds levels and a soundtrack, tests the gameplay, and keeps improving the build. Along the way, see how programmatic tool calling, Max Reasoning, and subagents help it take on longer-running work - using a sandbox to process tool results, split work in parallel, and bring everything back into one polished game. Check out the game here: https://asterism.openai.chatgpt.site/ Chapters 00:00 Introducing GPT-5.6 00:17 Building a game in Codex 00:52 Programmatic tool calling 01:07 Reasoning and subagents 01:35 GPT-5.6 in the API