Let's talk about Minecraft. (The in development version)
Ok, first off watch these.
Link 1
Link 2
Link 3
Did any of that interest you?
Now what is
Minecraft? Strictly speaking it is a currently only a sandbox game, but it is going to be so much more. This game is under constant development. Notch (The game dev) in the last 3 weeks has added: Doors, minecarts, Signs, and stair blocks, waterfall physics, buckets (which are awesome), saddles to ride pigs, and randomly spawned dungeon areas.
Assuming he meets half of his promised game features (Zombie Siege, Dungeons and Levers, NPC settlements, dragon lairs, motors for the carts, boats) it has the potential to be the best PC game of
all time. In fact as soon as he gets the multiplayer working it's going into beta!
Have a look at his site, try the free version
http://minecraft.net/survivaltest/ (It's is a very early build of the infdev), read the forums, look at what the people do with this game, and then get out your wallet and pay the man 10 euros (20 if you wait until it hits beta, which is soon)
I bought this game a while ago, and back then I thought it was worth the 15ish dollars I plunked down for it. It's kinda like playing a really good Lego PC game.
Five Stars, I recommend this game to EVERYONE.