I went and looked at the FAQ and saw this:
Q: How do you create this game?
A: I've programmed everything with C++ and DirectX (OpenGL for the first version). For the voxel sprites, I created my own voxel editor.
this man right here is a genius
i'm saying this entirely based upon the fact that he's using the words "programmed", "with", "C++", and "DirectX" in the same sentence.