Right, science time. Imagine the characters of Left 4 Dead within an MMO: normal, heavily-armed people in extraordinary circumstances, surrounded by NPCs with intelligently scripted and well-acted voices and whose pretty ladies don't have up-front areas that come with a jiggle function.
Your next step is to remove the sprint abilities of the zombies and tie them into the Norse myth of undead mariners that was covered in Sylvester McCoy-era Doctor Who adventure The Curse of Fenric. Next: mix in two tablespoonfuls of Alan Wake, alongside a pinch of John Carpenter's The Fog. What you've just laboriously produced in your mind's eye is (with some help from H.P. Lovecraft) Kingsmouth: one of the early locations in The Secret World – a game that's fast becoming one of the more fascinating prospects around in modern MMOs.