Nice graphics and fairly satsifying combat, the audio design and effects around the coin explosion felt good and the health bars also felt nice and responsive! Would have been more engaging for me with more going on and the ability to shoot in multiple directions but I get that that isn't the game type you're going for.
I think I ran into a bug after collecting my first power up and pressing pause. When I closed the pause menu again, the screen would no longer move up and so I couldn't continue.