I stumbled upon this little gem in one of Notch's twitter posts yesterday.
It is yet another "Block" based sandbox game. But this one goes a little further than the rest and adds Multi-Sized blocks, Triangle blocks and many many other kinds. This of course lets you build even more details works of art and in my opinion looks to be a really great game. I am super excited to see where he takes this and if he can get this to a final release I think this will overtake Minecraft in terms of "OMFG WTF Constructions".