A friend and I bought this game together and played it co-op, so I didn't get a chance to play the campaign single player. Don't think I'd want to. You work as a team of 4 - something that I realise is becoming a very generic amount - to stop the bad guys from using a chemical named 'FUSE'. As you progress, you pick up skill points with which you can improve your stats and learn new abilities, which really adds to the excitement of the game. Although, we didn't seem to use the extra abilities all that much, but maybe that was just us. But once you learn to use your character well, it becomes really easy and a lot of fun to kill massive hordes of enemies. And, on the off chance that you get bored of your character, you can switch to any other member of the team. I feel that the game should have done a little more to make you have to switch player and perform tasks according to the ability of each character - I didn't feel as if switching character was a necessity, just a thing you could do if it got a little monotonous for you. And it does get pretty monotonous at times. Complete a wave of enemies, go forward a couple of room, complete another wave of enemies, pick up some ammo, complete another wave of enemies, chapter complete. Some of the chapters were a little dull and repetitive but the enjoyment of using your character's gun really offsets that, so you don't feel it all the much, it's fun. There is definitely a lot of room for improvement, but I'd definitely recommend it for anyone looking to play a fun all-out shooter with a friend.