More structured, malevolent, less themed, and original, I think. Some rooms are literally endless savannah, etc. It's like one of those TV shows like sliders or quantum leap, each room is a puzzle as well as a fight, the puzzle being 'how do I leave'. Some are just stone rooms but trap you in some way. Others don't trap you, but if you interact with them in some way can screw you over.
EDIT: It does have the teleportation/summoning restriction, though, but that's more of a necessary thing to make survival horror survivaley.