Hey, nice project. I'm not a fan of the genre, so maybe my below points were intended, but here are a few things I would consider to improve:
Player hitbox - is kind of impossible for me to understand when the bullet gonna hit me or not. Some seem to pass-through,
More contrast in backgrounds - light bg makes it harder to spot bullets,
Things you collect with different colors and bullets - also would be a bit easier to differentiate them.
But as said, I don't know the genre, and maybe it's supposed to be this way^^. Cheers had some fun with this one.