Wow, visuals and music are wonderful (only menu is ugly and hard to read)! Gameplay is good, but some things you should improve:
1. Maybe I'm old but I was confused and my eyes was in pain because of the fast background sliding
2. At the start I was confused by the clouds, I tried to avoid them because they spawned and moved fast like some obstacle
3. I was confused by this tunnel at the center, I thought that this is a space where I can only fly (later I noticed that I can fly to the side borders of the screen)
4. I understand this small hitbox mechanics, it gives to the player more space to avoid bullets, but in my case it was confusing because I always tried to avoid bullets from hitting whole plane, not only the core