Very fun game. The idea is simple yet rather orignal and works well making for unique and satisfying gameplay. Great job!
I also appreciate there being a tutorial level explaining the game through gameplay and not just text. That's not something many games have though could use.
It's cool that the sound of crushed enemies gets higher when getting a combo. What would make it even more rewarding would be having score numbers pop up when destroying enemies which would also give the player a better sense of how many points they've earned.