The idea is pretty cool. I liked how the music disappeared on level 4, and honestly that loop back gave me quite a pleasant surprise. The boss fight is quite challenging, and I didn't manage to beat it. A health bar sure would've been nice, cuz i didnt really know how many hits was needed. As for the music, it can get slightly repetitive after a while. Also- when I first went from level 1 to level 2, I actually didn't know the shovel collected from level 1 would stay, so I ended up going all over the level to find the shovel, before finally realizing I already had it, so having the character be holding the shovel would've been a nice touch. Finally, getting damaged sorta instantly sometimes when moving onto the next room wasn't nice. But overall, I'd say it's pretty solid.