Minecraft

It's about time a thread was made for this game. The premise is simple: you're the only guy in the world (unless you play multiplayer) and by day, you can do whatever you want to manipulate the environment. But at night, zombies and skeletons show up and try to kill you. The world is ever expanding horizontally, so you can keep going and going and going and going. However, if you dig deep enough, you'll eventually hit lava. Here are some videos to give you a general idea of the game and what you can do with it.

http://www.youtube.com/watch?v=myb4fmwpMM4

http://www.youtube.com/watch?v=LWPk5zlKAEM

http://www.youtube.com/watch?v=LnjSWPxJxNs

its like 10 euros, which is 13 or 14 USD. well worth it. they should change the name to Minecrack.. Playing in a snowy landscape while listening to Gentle Jena from Planetarian is a surreal experience. especially when you get scenes like this:
http://cl.ly/2YHb

the graphics are purposefully chunky like that, and the dev team is one person.