As far as I can tell this is Left 4 Dead: Games Workshop Edition. Having never played the first one, all I really knew was that this is a PvE match based game with classes that you play in a group of 4. It's really well optimised, and the intro quest is good. After that though you're basically just chucked in to a matchmaking hub area and thrown in at the deep end. No story, no NPCs, just matches with random people killing rats. All my matches were half bots, half people, and I was usually thrown in halfway through a map anyway so I had no idea what was going on. Good perhaps if you know what you're getting into but otherwise alienating and boring.