BattleField Bad company 2 Sandbox:Must Buy
Black & White 2 is a great city-building game, however eventually you will "win" the land by impressiveness unless you use a trainer to lock your city's impressiveness to a low value. I always find myself replaying B&W2 because of its city-building.
http://forum.blockland.us/index.php?topic=145324.0
is Go-Mod like garry's mod, except using half-life instead of half-life 2?
Kind of, but I don't believe you can weld stuff and things like that.