Nobody ever seems to talk about Prey [http://en.wikipedia.org/wiki/Prey_(video_game)]. But it's pretty interesting. Your guns are all living creatures. Although beyond that, they're pretty much just your typical assault rifle, SMG, energy gun, grenade, etc. But they LOOK pretty unique. Like, the assault rifle has a button which makes a giant tentacle shoot out and latch onto your face (your own face), which serves as a targeting system for the sniper rifle (which it morphs in to). It's a cool idea. There's another gun that can suck up fire or electricity out of the walls and shoot it at people.