Is GPT-6 Astra Really That Good?

Is GPT-6 Astra really a whole level above Claude Fable 5.1? I gave both AI models three increasingly difficult challenges in Blender and Godot to find out. Same briefs. Same rules. Up to three subagents each, with no spending cap. They could build, inspect their work, fix problems and repeat. Then I compared the results, tested the interactive projects and looked at the recorded API cost. The three challenges: • CLOCKWORK — build a detailed clockmaker's workshop inside an old clock tower, with a working mechanism and moving gears. • SNOW — create snow that deforms under a rolling ball, holds footprints and reacts when you click it. • WINTER HUNT — turn the snow idea into a small third-person hunting game with a character, a gun and birds to hunt. From Blender assembly timelapses to gameplay comparisons, we look at what each model actually built: the visuals, the interactions, the rough edges and the final verdict. Chapters 00:00 GPT-6 Astra vs Fable 5.1 00:35 Round 1 — the clockwork challenge 00:59 Building both Blender scenes 01:40 Clockwork results and cost 02:37 Round 2 — interactive snow 03:01 Testing Fable's snow 03:46 GPT's snow and the comparison 04:43 Round 2 costs 04:55 Same rules, subagents and autonomy 05:11 Round 3 — Winter Hunt 05:28 GPT's hunting game 06:15 Fable's hunting game 07:11 The final-round comparison 07:27 Who wins the three challenges? 07:41 Recorded costs and final thoughts Models: GPT-6 Astra · Claude Fable 5.1 Tools: Blender · Godot Cost note: The original three tasks have recorded API estimates of $390.60 for GPT and $472.04 for Fable, including subagents. GPT's final round has one interrupted response without final usage, so its recorded amount is incomplete. These figures exclude later viewer work, subscriptions, local rendering and video production costs; they are not a complete production bill. Which version would you choose in each round? Tell me your picks in the comments, and subscribe for more AI building experiments. #AI #Blender #Godot #GameDev #GPT6 #Claude