AAA studios spent 5 years building this.

Claude Opus 5.5 did it in one session.

No engine. No assets. No shortcuts.

It built a 4KM city in a browser.
three.js + WebGPU. Oneshot.

You can drive it.
You can fly it.
You can send a drone into windows —
rooms load as you enter.

Rain on everything.
8 districts.
Full procedural.

One session.

Now imagine it running for a week.

This is not a game engine.
This is what AI does when you stop limiting it.