I think it does look much nicer than the other examples of this nature that I've seen.

I would guess they are pre-generating the world from the image, not generating it on the go as it runs reasonably well, but doesn't this really limit world size?

I noticed some solid geometry that is accidentally transparent.

The stuff behind the camera looks pretty good, which is presumably fully generated, so if they can make it so you can actually move around more, and with similar quality it could be interesting.

I do wish the examples had a full screen button, the view is tiny..