I love the idea of switching between 32, 16 and 2 bits.
I love the music and visuals...
Maybe I would change two things: in level 3, I would rotate the player towards the mouse cursor and rotate enemies to show where they will shoot. In level 1 I would change colors so enemies, the player and projectiles would be distinguishable. I’m rating the presentation 5/5, so don’t worry. I understand that you might not want to add these changes in order to stay as accurate to the original style as possible.
Man, this game was irritating at some points. I felt frustrated in level 1 because everything blended together. Level 2 was too hard. It would be nice if checkpoints were at every sub-level, instead of having to repeat the entire bit era every time the boss kills me — especially when I don’t like that era.
Connection to the theme, presentation and creativity are your strong side.
P.S.
I think your request to finish the game before rating is too much. Rage-quitting or stopping a game you don’t enjoy at a certain moment is completely natural, and as a game developer, you shouldn’t push players into these decisions.
I think you could design the game backwards, so it becomes simpler over time and shows your best skills at the beginning. That way, everyone might be happier.