A simple 5D arena (or pair of arenas, to be more precise). The name comes from the orientations of the hills (which aren't actually hills, unfortunately).
A central arena with lots of twisty passageways and out-of-the-way sniper perches spread around. A nice feel to it, although some of the staircases are hard to see around.
Two levels. The bottom is a maze of twisty passageways, with a few hiding rooms. The top is a more open circle-and-cross based around a raised pool (but still tight).
A weaponless square ring, for two contestants to duke it out. If you leave aliens on, you'll have the added challenge of dodging fusion bolts from clueless bobs...