To me, a level has to look like it would actually exist somewhere. In an intelligent alien world there would probably still exist aesthetics when designing a building, and we would notice those even if their culture and architecture was radically different from our own.

What I like about Ryoko's work is that his levels look like they could be real, and that they'd been designed by an alien architect.

That's not to say that Ryoko is alien... maybe he is... maybe not....

Anyway, that's beside the point that these are gorgeous levels, very playable, don't immediately reveal their secrets so they're fun to explore, and nicely spread the carnage all over their rooms, instead of focusing it all in one place. These are good for hunting, sniping, all weapons, and warfare styles.

They do slow down a bit on older/less powerful CPUs because they are complex, but that is the price we pay for great environments.