Ok this was AMAZING!! I can't even imagine how much effort went into the pixel art, it looks crazy good!
Controls were snappy, responsive and really drove it home with the knock back when throwing the pickaxe(my favourite control by far)!
Enemies were challenging and it was fun trying to balance different stats in preparation for the next levels. They also had good variety, so it didn't feel monotonous!
The transitions between different sections were also really good(e.g. from end of level -> upgrade menu -> next level), all by focusing on the drill
The music is also really fitting and I love the boss theme, it really helps build tension!
Only thing I would nitpick is that I could see some crystals in certain areas that were too high to reach and not reachable by the throwing pickaxe and certain enemies(like the fire breathing one) get stuck in the platforms where you can crouch to go down. Again, these are minor, but these were probably the only improvements I could think of!
Incredible job on this, this game really is one of the best in the jam!