I really like the idea of not being able to control the player and instead protecting them from monsters. This game is a pretty great execution of the concept, but needs some polish to really hit the mark. As others said, some sort of hit flash or other indicator for damage is near essential and some sort of progress meter for the objective of each level would be nice (time for timers, health for bosses). Speaking of, it seems the boss is missing its hurt box, as it is also entirely unaffected by the secondary freeze zapper. These things are small nitpicks though, great job completing the game!