This game is very cool! It's a clever idea with pleasant geometric visuals, and the music and sound set the mood perfectly. I don't think I'd call it a bullet hell game, but it's neat so I don't really care ¯\_(ツ)_/¯
I think the level design could use a bit more work to ensure that gameplay is always fair, because I encountered points where damage felt unavoidable or very nearly so. The spinning cross on the top-left of level 1 was a particular offender: it splits space into four sections with no indication of which one the player should head to. Choose correctly (the left) and there's a decent chance you'll avoid damage just by luck, but choose wrong and it feels/maybe is impossible to avoid the sweeps that move across the stage while the cross is turning.
That said, I liked this game enough to capture video and review it frame-by-frame to try and give precise and accurate feedback. This is a great prototype and I'd love to play an expanded version with more levels, designed with more fairness in mind.