Jeevz told me about this mod, called DayZ, for ARMA2 OA which is currently still in Alpha but a lot better than most AAA games.
You have the whole island of Chernarus to wander around and up 50 human players to play with or against depending on how you want to play, and AI zombies that multiply as the real-time game progresses. It is highly realistic and has a full night/day cycle to match where the server is hosted. You have a certain amount of blood (your health really) and if you are attacked, shot, don't eat or drink you lose blood and must bandage, eat/drink to stay alive.
You start with a Makarov and 5 mags, a water bottle (fillable), a tin of beans, flares and your humanity....
Scavenge (or kill) for food, water, weapons, ammo, car/helo parts to stay alive. Just like in The Walking Dead, the zombies aren't the worst things in the game, your fellow players are. If you murder someone you lose humanity and become a bandit and wear different clothing and other players will shoot you on sight. You can kill a bandit without consequence though.
It really is a battle to survive and no matter what server you go on you have a saved player file and you will always start where you ended last time with all the equipment you had.
I am a bandit at the moment. I was trying to head north to get away from the bandit ridden cities in the south and had managed to scavenge a watch and an AKS-74 with a Kobra sight and 3 mags. Moving north I heard someone behind me, turned and there was a player stood looking at me, pistol outstretched, well I put 5 rounds into him just by shock of seeing him behind me and killed him. I became a bandit (

) and looted his body. Found a backpack (bigger than my patrol pack), 6 AK mags, a 1911 and 5 mags, water, chem lights, a compass (best of all that was!), map, food, cans of drink and loads more stuff which fitted into my newly looted backpack

He was furious on the chat lol, but he did come up behind me and did feel like he was trailing me. Just a little glimpse into the great mod.
Thanks for the heads up Jeevz.