I dunno. Maybe the same art/graphics style (more specifically, macro-cubic character design and textured macro blocks on the map).
Anyway, I'm not saying this game sucks (just couldn't, since I never tried it); it surely bests Minecraft in other aspects (like gameplay, lore or something). I'm just saying that mostly those who differs on that aspect are The Sandbox and Teardown, and can't see nothing more like these two, when it comes of Voxels. Thus Minecraft has become the biggest referrer for Voxels genre.
That might be your answer.