It's a voxel game based on OpenGL. It implements much of vanilla minecraft. Annecdotally, I'd say it performs much better for me than minecraft itself does, at longer view distances, and with essentially no observable GC pauses (of which minecraft suffers quite visibly). Also, a stabler heap size, etc.

The capabilities are definitely there.

I'm spending some of my weekend moments playing around with more GL stuff based on what I've learned from reading this project, and it's quite fun. Build times are right up there where you'd expect, too -- seconds or less! (The first build takes a few moments for running gcc for the c bindings to GL, but after that, those cache nicely.) A 1-second turnaround for recompiling a whole game is an incredible breath of fresh air.

And of course, I shipped my demo game to a friend on a mac the same day I started writing. I'm on a linux. Not bad.