Thanks for playing and getting all the way to the end!
For the boss, I can see how it's confusing, he's vulnerable when he's in the loading animation and dashing into him deals damage. I wish I had a bit more time to playtest it and get feedback to improve on the visuals for the fight.
I wanted to do a global script for the music but honestly that was one of the things that was added in the last few minutes and I completely forgot to make it so it doesn't restart every death haha!
As for hitboxes, that was another issue of not enough playtesting which led to certain parts being extremely difficult so I can understand that it's a bit frustrating (sorry about that)
It was hard to balance out the dash and change its values as that would require re-building levels to account for the speed change which unfortunately wasn't feasible within the game jam period.
Thank you again for playing and for spending so much time going through the game and leaving a lengthy review. I agree with all of your criticism and wish I had just one more day to fix all these problems haha, but maybe I'll polish it up once the jam is done. Your game looks interesting so I'll make sure to give it a try! And you got a great time also!