Doom

Mother of all First person shooters (ok, wolfenstien was first but it was boring). In this game you are stuck on one of the moons on Mars guarding the geeks that work there and then a experiment goes wrong (like they always do) and the portal to hell opens up and demons attack and rip your friends apart. You need to slay the hordes of hell and stop them. Fun both in single and multiplayer, co-operative rules . Coolest weapon must have been the plasma gun and the chainsaw, I like the idea that they had any use of a chainsaw in space :)