DayZ is a zombie apocalypse survival mod for Arma 2 which really caught my attention. It has a lot of the aspects I've really yearned to see in a multiplayer zombie game. You play in a persistent world (split between an ever increasing amount of servers) which is roughly 250km of mostly rural landscape in an Eastern European setting. Gameplay is completely freeform/sandbox where your goal is simply to survive and scavenge weapons/food. You'll interact with other players who might team up with you, or they might kill you to take your stuff, or they might feign friendship and betray you later. I'm thinking of buying Arma 2 just to get this mod. I've watched a bunch of Let's Plays on youtube and it's so interesting to just sit and watch.
http://www.youtube.com/watch?v=8gEMpcBTnJk
