That was amazing, thank you for making this! Really enjoyed playing it. So cool that it's actually improvised :) On my second attempt I found a spot in the boss-fight where I could just stay still and the projectiles would miss me... It could be cool to add rhythm or a way to charge shots to incentivize not holding the mouse-button down. Also if there was some way that the loop played a bigger role, for example if enemies you miss re-emerge on your next orbit or something.
Bravo!