This is a cool game, I really liked the music and the shooting sound effect feels awesome!
I would take the time to put in some type of in game tutorial, at least the button prompts in the first room.
I was also confused about the pickups. When it was spinning I had no idea what to do, it wasn't until a couple minutes in I realized the symbol above them is an E and it was rotating too. If you want to keep the rotating effect on powerups, make sure it's just the powerup that's rotating and not the E as well so it can clearly be read! It would also be kinda cool to be able to read what the powerups are before you pick them up, unless your intention is for them to be totally random.
I also ran into a bug where I picked up a powerup and killed the boss at the same time, so my game locked up.
Great job! 