GPT-6 Astra 'finished' RimWorld in 15 hours — chinchilla included

On September 6, a Japanese RimWorld streamer announced that OpenAI's GPT-6 Astra had cleared the colony sim entirely on its own: roughly 15 hours of actual play, ending with every colonist evacuated from the planet — the starter pet chinchilla included. The claim traveled as a screenshot of an X post by @Apocriton onto r/singularity, where it drew roughly 1,200 upvotes and more than 240 comments within two days. OpenAI has not commented.

Apocriton says the only instruction given was, in effect, "judge everything yourself and clear the game." Astra then drove the colony with computer use, web search, and external memory files it created and consulted on its own, surviving consecutive raids to clear within 1.5 in-game years — "about 15 hours of actual operating time," per the post — on the Cassandra storyteller, Community Builder difficulty, display mods only, no DLC, via the ship-launch ending. Per the screenshot, the tweet had roughly 87,000 views and more than 900 likes when it was captured.

RimWorld is a story generator rather than a game with one win state: crash-landed colonists build, farm, and fight raids while a "storyteller" AI throws events at them, and most players never leave the planet at all. The run's stream archive is on Apocriton's channel, and he later shared the memory files the model wrote — a play log, a completion report, an "escape evidence" JSON — alongside the underlying ChatGPT conversation. Where last week's Portal run, covered here, froze the game while its agent reasoned and published a $571.18 token bill, this setup bridged RimWorld to Astra through an MCP mod and leaned on the model's own judgment throughout.

The thread's skeptics had two objections. One was lookup, not mastery: "It googled the min max strategy and applied it? This is the same as looking up the Rubik's cube tutorial and claiming you can solve one," wrote one commenter, while others noted that RimWorld speedruns take about 20 minutes with copyable strategies — and that a "story generator" finished in 15 hours is itself a judgment call. The other was the missing ledger: the thread's OP conceded "OOP didn't provide the exact numbers, only that he literally burned through all of his tokens." RimWorld's age — early access since 2013 — also puts it squarely in the training data.

Then the game's designer weighed in. Tynan Sylvester posted that Astra "can play RimWorld to the credits screen all by itself," calling it "an inflection point in AI capability." For a long-horizon sim with no single ending, that endorsement — from the person who built the game, not from OpenAI — is the strongest signal yet that the run happened as claimed. What would settle the argument outright: a token-and-cost ledger like the Portal run's, and a second model clearing the same colony from scratch. Chinchilla optional.