The home page of this site is a small 3D world. Seville, San Francisco, Canada and New York in one landscape, lit by your own clock, with my beautiful face as the sun / moon.
I built almost none of it. I just set up an argument between agents and went to bed 💤.
Inception
In August, Matt Shumer posted a game Claude wrote from a single prompt. 3.8 million views, half the replies calling it fake. Then he explained the trick:
The agent (not you!!) breaks the goal into parts, gives each part a specialist builder and a ruthless blind critic sub-agent, with a mandate to only pass if the generated artifact is better than some real-world equivalent.
He calls it the Gauntlet Loop, as in running the gauntlet: the work walks a line of critics and takes its hits. It is kinda a GAN (Generative Adversarial Network) rebuilt out of agents, a generator making things and a discriminator judging them against the real thing, except the two do not trade gradients. They trade insults.
Here, one agent builds my mountains. A second agent, clean context, no idea what the first one was going for, pulls up a real screenshot of Monument Valley and says which of the two is better.
Round three: ten pieces of the world, ten critics. Best score 7 out of 10, and all ten picked Monument Valley.
the near sea is a view of the seabed, not a view of water
the gulls are not birds
Agents have no feelings. That is the whole trick. A critic with a clean context has no friendship to protect, so it costs it nothing to be ruthless.
The night
The loop started at one in the morning on 16 August. By 08:46 it had done seven rounds and fifty-two commits: one continuous landmass with a river running in its own channel, and the Golden Gate standing in open water instead of on it. The sun and moon were already running on real solar math from your timezone.
That is the part of the story people want, and it is the smaller half.
Making it mine
The loop gets you to good. Good is not the same as yours.
A fresh critic asks "is this beautiful". It will never think to ask "would Miguel like this", so it hands back something competent that could belong to anybody. I wrote the answer down in a file and made every agent read it before touching anything. Even then, the world needed a human dropping by to file the kind of bug report no studio has ever received:
The birds hang in the wind like laundry. I think they might be pelicans, and I would like them to be pelicans, that would be awesome.
The balloon is an egg. Nobody has ever pointed at the sky and said look, an egg.
On that small island to the left there are a couple of cones that look nothing like a fire, you bastard.
The agents treated all three as serious engineering. The birds are pelicans now and fly like pelicans. The balloon is round. The cones I swore at turned out to be my surfboards. I could not identify my own surfboards.
That refining pass was the part I enjoyed most, and it is where the easter eggs got in: the world now reacts to a few things no page needs to react to. Try clicking the plane. On second thought, don't.
The inner pages went through the same loop, including the one you are reading. My favorite bug of the whole run was a pale rectangle in the night sky, which came down to a single star glowing past the edge of its own cell.
An agent swarm will hand you a beautiful world overnight. Whether there are pelicans in it is still up to you.