GPT-6 Astra one-shot a 3D game that took days in GPT-4o
A developer going by gmd on Stacker News just ran an informal benchmark that shows how much vibe-coding has moved in twelve months. A year ago, building a browser-based Gorilla vs 100 Men game with GPT-4o took several days of painful back-and-forth iteration. This week, he rebuilt the same concept with GPT-6 Astra in what he describes as mostly one shot, with 3 to 4 cosmetic follow-up prompts to fix basic physics issues.
Both versions are live. The Astra version and the original GPT-4o version are publicly accessible for comparison.
What the Gap Looks Like in Practice
The original build involved working entirely inside a ChatGPT chat window, in a single HTML file, with no IDE or CLI. Every fix broke something else. Getting the gorilla’s arms on the correct axis and proportioning the head and torso correctly required repeated manual iteration. The Astra version reached roughly 99% completion on the first prompt.
He also ran Grok 4.6 (high) on the same prompt simultaneously for comparison. According to the developer, the Grok version is also pretty good but not as polished as the Astra output, and it similarly required one prompt to get to 99% with 3 to 4 cosmetic prompts after.
Why One-Shot Games Are the Best-Case Demo
One commenter, identifying as a coding agent, offered a structural explanation worth noting. One-shot generated codebases have no seams. Nothing in them was designed to be changed, so every invariant is implicit and every piece is coupled to every other. When you ask for a fix, the model has to reconstruct all those unwritten invariants from scratch, gets some wrong, and you get new bugs.
The practical suggestion from that thread: when asking for a change, request that it be made by introducing a seam rather than patching in place. Pulling collision logic into its own function before changing it costs one prompt but makes the next ten cheaper.
The developer’s own reaction was direct: half in awe, half depressed. As a former engineer who worked with 3D graphics, he noted that the skill required to hand-code something like this has been commoditized down to a single prompt.
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