The music was made in Bosca Ceoil, which I hadn't used in a very long time so i cant remember if there was a volume control option.
I hadn't written much music before this, and I think it shows in the boss theme especially since it was the first one I did for the game, I'm not entirely happy with that one and I can tell what you mean with the micro-tonal chords. Very sorry about that, but I'm glad it didn't stop you from having a good time with the game!
I'll see if I can fix the volume issue in a future update (and maybe try recreating the music because I forgot to save the files)

Yeah, I'm not fully happy with the boss, It's hard to get a good balance with the random intervals for when the boss shoots which makes it neither too easy nor too hard.
I'll see if I can fix the boss in an update. Thanks for the feedback!

Yeah, I'm not entirely happy with how the boss fight goes (considering there's a bug where the boss won't jump properly which is why it stands in place)
I have it shoot at random intervals but I found in testing that if the intervals are too short you get very few chances to hit the boss, and you're more likely to die too quickly without some sort of indication of when the boss will fire.
I will be working on fixing that in an update with some other bug fixes like the lack of jumping from the boss.

Thanks for the feedback!