Completed the game, got around 25k points, spammed the final boss with arrows, he couldn't even hit me. Found a bug: you can hit enemies with a pickaxe through a 1-tile thick wall.
Enemies were a piece of cake earlier in the game, but when they start spawning in groups of three, you have a problem. Cause you've just reached a new level, the bats appear, and you have to run away from them to line them up with your shots, but the rocks are blocking your way, cause you haven't even started mining them yet, and it feels unfair.
I feel like it has potential, but needs more content. More enemies, some upgrades, etc. I'd also say that different kinds of rocks should drop different kind of minerals, now it seems to be random.
The pixel art is cute, though.