Day z, an arma II zombie mod

[doggypwn]

And to add to what crash said, there's a notorious hacker on DayZ who goes on random servers and does crazy stuff for laughs. Jef has an incident recorded in which a certain hacker spawned in old lady NPCs that followed people around and had compasses, maps, and radios on them. The people on the server who didn't read the chat and were new to DayZ, who had no idea that admins on servers can't spawn things in, passed it off as a gift from the admins. I've heard of incidents that were more game-breaking than stuff like that, as that is relatively harmless. There have been things much worse like mass zombie spawning and people being teleported to one area.