No one has ever heard of Arma2, but in the past 2 months its mod, DayZ, has shot up in popularity.
http://dayzmod.com/?AboutIt's an "anti-game" multiplayer Zombie Sim where you spawn on the beaches of a map that is 252 square kilometers with 1 bandage, 1 painkillers, 1 flashlight, and 1 backpack. That's it. You have to go out and find food and water before you die of thirst/hunger in a few real-time hours. You should also find some sort of weapon because nothing you spawn with is a weapon, and zombies tend to fuck your shit up. There is no regeneration of your health in this game; it is set at 12000 total blood that you will start to lose if you are hit. When you're hit or shot (by other players) you will start to bleed out uncontrollably until you bandage yourself with your one bandage or others you find. The only way to get your health/blood back is to use a bloodpack to have a blood transfusion, but this requires the assistance of another player. Find a gun or ax for protection, get a surplus of food, get a bigger backpack, then fuck up every other player you come across. By the way, this game is in real time based on the server location. If it's night for the server, it's night in game, and nighttime in this game is a whole different subject. Your character is also "persistent" across all DayZ servers; you have the same guy with the same equipment in all of the servers even it you logged out or just played on a single server.
Also the average lifespan of a player is officially tracked at 35 minutes.