I haven't played it, but I hear tell that MineCraft is basically the equivalent of crack on a stick. It's an awesome game that doesn't cost much, but hooks you deep in your core so you can never give it up. But maybe you're cheap, or, like me, you just haven't had time to check it out. Well, do it now because it's going to be free for the next few days it sounds like.
Something got messed up with the game's authentication servers thanks to a sudden increase in the game's popularity (I'm going to guess Penny Arcade had something to do with it) and instead of shutting the whole @#!*% thing down and not letting anyone play, MineCraft developer Notch has decided to instead let everyone play for free for the next few days or whenever he gets it all fixed up. That's pretty much a cup full of amazing.
Go here and play as I will be doing the second I finish The Last Station. You should watch that movie too, but play MineCraft first.
Mine, All Mine: MineCraft Free Weekend [Rock, Paper, Shotgun]