A bit more feedback: I like how the powerup-loss effect happens when the player is only one hit away from death (or two hits for certain weak enemy attacks or high-HP characters), as it functions as an in-your-face warning that you're about to die and should be more careful. However, there's no such warning during boss fights, where the player is immune to losing powerups; it's just the same as every other taking-damage animation until suddenly you're dead. The most that happens is that your tiny health bar in the distant corner of the screen subtly glows red. It'd be nice if you could add some type of more-obvious low-HP warning for those situations as well.