I am sure most of you already heard about this game...
Minecraft is a Sandbox/Survival/Adventure game about placing blocks to build anything you can imagine. At night monsters come out, make sure to build a shelter before that happens. It also has music by C418! And it is very addictive...
Minecraft is currently in the "Beta" stage... Im playing minecraft since alpha... Oh and yea MC supports multiplayer so you can go play with your friends and build all kind of awesum stuff.
An awesum fanmade trailer about MC:
http://www.youtube.com/watch?v=v5fS4RF3ht0