Wow, this is a fun entry! Hype music, with a frantic merging of top down bullet hell stuff with rhythm stuff. I like this concept a lot after playing through it. I also loved how the skull beams were tied to how many rhythm moves you missed, very clever.
I should mention that the game crashed towards the end of the boss fight while I was in the browser. I did go back and finish it, and was rewarded :). Also, I felt like the arrows were sometimes off beat? Other than that, great game feel and sounds. Awesome work!