This is happening right now. Minecraft creator Markus Persson is currently taking part in a video game competition to make something new in 48 hours - and you can watch him doing this - live.
I've just began keeping track, so I'm a bit out of the loop, but it appears as though the game is currently up and running. This sort of stuff is fascinating to see for me, as a layman. For those with a knowledge of game design and programming, it's a must watch.