Yes that looks like some bad parallax mapping, but if you look at other screenshots you can see the bricks are actually modelled.specially when you look at the walls and the top of the tunnel, it doesn't look like true stone and bricks, it looks like a heavily displaced polygonal surface with a weirdly wrapped texture
No idea of the ratios of either as I havent seen the game in the flesh, but its obviously more detailed than any other existing game polygon wise.
Every 'normal'(*) game has mesh clipping theres no way around this and even if you made it so theres no clipping, the gameplay would most likely suffer, i.e. realism != more fun.That, and the fact that many times I see objects going through other objects
I do agree with what you're saying about very high res making it look worse, have you noticed when ppl make these small gif's of a game in motion they usually look much better than the actual high res screenshots
(*)i.e. not tetris etc