We're excited to announce that we've fully migrated the Xbox Forums to their new home, here on the Microsoft Community forums!
As of today, going to forums.xbox.com will redirect you here to the Xbox area of the Community forums. We've moved all of your existing threads over so you can continue and start conversations with the new forums experience.
We sincerely appreciate the feedback you have provided over this transition and can't wait for you to check out the new Xbox Forums!
Along the lines of DayZ? Well...there's not many games out there that are along the lines of it...for Xbox anyways. Dead Island would probably be as close as you can get for a zombie open world game. Far Cry 3 is a pretty good open world game as well.
^ but op is asking for multiplayers with open worlds...metal gear is just open world, not multiplayer.
the best bet for games out now have already been suggested; gta 4&5, rdr, dead rising 3, defiance, dead island...i think crackdown has 4-player co-op...not really open world, but the maps in world of tanks are pretty big.