Sorry if there's already a thread about this game, didn't see it!
http://www.youtube.com/watch?v=UVFTmqXFLX8Minecraft is a sandbox game which allows players to build constructions out of textured cubes in a 3D world. It is currently in development by Markus Persson, aka "Notch". The gameplay is inspired by Dwarf Fortress, RollerCoaster Tycoon, Dungeon Keeper, and especially Infiniminer.
So basically this is how the game works: At daytime you can roam the world, craft things, mine and so on, but during the night monsters pop so you have to protect yourself until dawn.
It's amazing just what you can do in this game, it feels like there's no limits.
The game is currently in Alpha and costs 10 euros.. although there's a free "classic" version but that one is lame (can't craft, no mobs, etc.). The game is going to enter Beta this or next month and the price will probably rise too from 10 to 15 euros.
www.minecraft.net