It wasn't Minecraft, though, that inspired me to create Sproxel. Minecraft represents the world as voxels, but it doesn't go whole-hog with the technique. It still overlays polygon characters into the world - they're blocky, but they're not created out of the same building blocks as the land. It took a yet-to-be-released game named Fez to really pique my interest.
Fez uses a technology they call trixels to create an entirely new gaming experience. One second you think you're looking at a relatively low-resolution 2d game, the next you're looking at a bunch of 3d representations of the pixels you thought were flat! A second later, you're back to an ortho-2d view of the world, and your brain grows accustomed to thinking of the data as pixels again. This was such a good combination of retro, modern, and new game design that I just had to get in on it somehow!
Another game with a similar all-voxel approach to gameplay is Voxatron. Voxatron is also still in development, but it too is looking like it's going to be great.
Another youtube video shows Voxatron's own sprite voxel editor, but it hasn't been released yet, and I just couldn't wait to give game developers a tool they could mess with between now and when Voxatron comes out.
If you haven't seen these videos yet, hopefully they inspired you as much as they did me. With any luck, some talented engine designers are already working on their voxel-based engines, and Sproxel will help them make their dream a reality.