Nice spin on the theme, I think it really just needs some extra juice (more dramatic boss + music, some background elements maybe?)
I kept retrying after I leveled up. Would be cool if there was like a shop or something w/ branching power ups (ex. slow down the bar, maybe a shield, etc.) to add more variety than just bumping stats on level up
Would also be cool to see a challenge mode for a level 1/perfect run