When you first see Space Marine, with its third-person viewpoint, huge guns and beefed-up characters, it's difficult not to think that it looks a lot like Gears of War. The comparison is certainly justified. The name alone brings Gears to mind, along with rather a lot of other recent shooters. Then you see that the walking muscle of a main character has skulls daubed all over his power armour. And then, running straight up into a cluster of enemies, he brings out a chain-sword that bears more than a passing similarity to a chainsaw and hacks an Ork in half with it.