Arma2: Dayz Epoch mod
Dayz mod with base building thats different to wasteland, all driven via a crafting system whereby you gain wood from chopping down tree's, collect scrap metal, and use these to build your base up bit by bit. Every 20 minutes or so there are missions scattered around the map to gather weapons, medical supplies and supply crates.
There are trader camps all over the map whereby you sell and buy items using the mods in game currency of tin/copper/silver/gold/briefcases. You are either a bandit or a hero depending on your humanity and how many npc or player kills you have, also places like 'Area 19' on the map which are NPC controlled bases you can attack and loot.
Currently on a server with an amazing base in a barn, 2x garage doors with combination locks, 4 locked safes, tents, sheds, car storage, roof outpost, 100+ guns, hello kitty car and much more.
Well worth a go with some mates