Some people might be interested in Minecraft and all its glory so you can either get two versions, one being somewhat of a cracked version, or the real one. For the real version, go to www.minecraft.net and it will cost 20 euros. For the free version you can pretty much torrent it from any site like ThePirateBay or whatever you might use. For the cracked version you will want to run the .exe as admin and once the game is actually running, hit "Force Update" which updates your Minecraft to the current online version.
And that's how its done.