The Hill

The Hill is the dimension to which Mikhail Rasputin teleported the Morlocks just before he collapsed and flooded their tunnels. The entire world seems to be one giant hill, with Mikhail's castle at the top. The air is highly corrosive, and the weather patterns are totally different. The mutants there try to breed selectively to bear progeny strong enough to make it to the top of the Hill and become Mikhail's chosen. It is a brutal world, but something in the air makes all wounds non-fatal, so that even the wounded get up and try again.