Please help me figure out what pc game is use to play?

Okay there was this pc game I played a long time ago. I think its some kind of MMORPG and it was made before 2007. All I could remember was that the graphics were pretty good and you had some kind of gravity gun. You also had a option were you could have zombies or something attack you. You could also build things, I remember seeing some kind of cargo crate and you could move it around and put stuff in it. Im sorry for the little information but I would appreciate it if you could give me a name or at least suggestions.