Thanks for playing and finding the game fun! I guess some things I can improve on if I make another bullet hell is a more intuitive hitbox that pops out more!
You are right that it is nothing revolutionary or groundbreaking, I guess it is a slightly different approach to how bullet hells work as one ship mirrors you which indicates the ship that shoots bullets aimed at the player which works well with the rhythm aspect because those aimed notes are more impactful.
Since time constraints are a thing of course, the idea that was supposed to supplement the bullet hell, which was rhythm inputs corresponding to keys on the keyboard to represent a control panel, ultimately had to be cut. It would have made it more interesting as the player could shoot back at the enemy to gain score in each level!
Here is the github repo for this game: https://github.com/AtomicAntt/RhythmBulletHell