Though it blends a bit with the orange enemies, I really like the yellow lights in the background aesthetic.
I'm torn on the core mechanic cos on one hand it's a bit tricksy to use in a way that doesn't flow too well, on the other there's definitely something conceptually satisfying about it if that makes any sense. Like, there's a coolness factor, perhaps to having multiple components or having the projectiles transform of something.
I think the oddity of the game is how that idea clashes with flow. EG, having to stop to aim to shoot backwards at the dude, it requires too much focus relative. Perhaps if a wave was shot backwards?
Never really understood the build-up bullets, though switching between the other 3 attacks was interesting enough.
Perhaps some kind of explosion attack that can damage you as well would be interesting?
Edit: Oh, thought. Did you consider having shooting the enemies being the trigger for the effects instead? Obvs it would be quite a different game but it might flow better.