Really cool game idea, some amazing puzzle design, and the graphics, theme and music all work beautifully hand in hand. I didn't make it the whole way through as I got stuck eventually but had a great time with what I did play.
My one source of frustration was that pressing space and then the arrow keys to mine a stone often meant that if I mishandled that interaction a little, i'd move through earth instead when that wasn't my intention. I would have preferred if the arrow keys were reserved for burrow movements and mining worked a little differently so I don't accidentally mess up my pathing and have to restart.
Superb submission!