Fun game!
I love the art style and music, both give off a sort of clean arcade feel that matches the gameplay very well.
Primary concern is balancing. The enemy will usually deal over 200 damage to you before you can get any kind of defenses to fight back, and from there it only gets ore difficult as the enemies are too fast and have too much range. by the time you can properly fight back you will usually only have 100 health left, and then you will soon lose due to the mines draining you.