This is a sandbox over Google's Photorealistic 3D Tiles. You walk a character around real cities, mapped from satellite + aerial photogrammetry.
To run it, paste your own Google Cloud API key with the Map Tiles API enabled. Google has a generous free tier; usage gets billed to your account, not ours. The key is stored only in your browser's localStorage — we never see it.
Tip: in Cloud Console, restrict your key to https://earth-walker.prometheus7.com/* + the Map Tiles API + a daily quota cap, so a leak can't run up a bill.