Add Minecraft to Team Fortress 2 and this is basically what you get. Build your defence, shoot and destroy other defences (btw, gravity exists, so stuff acctually falls and breaks when there's no support)
You might meet me there, my names [FF]Rambo and you can get the game for FREE here: buildandshoot com
At first you think it seems lame, you try it and BAM you are hooked for good 'cause you can't resist it
Pro tip for newbies; don't use the shotgun or SMG, start with the rifle, once you get the hang of it - you are unstoppable!