Great level, very long and labyrinthian.
Some issues:
This was a screen exit into another area but looks closed-off to me.
This area, if you happen to destroy the blocks as I have here, is a bit unintuitive how to figure out how to spawn the trampoline again. You have to like, go way right or left and approach it with the camera raised up high, then it finally spawns back in. Was this intended? Are you supposed to just leave and reenter the area? Seems kinda unclear I guess.
I was able to spawn the "you solved the puzzle!" music & red coin event again here as I was on the way out...yes, all the way down here where it should not be playing, lol. Try not getting both red coins the first time (I think that was the problem). Sweet li'l puzzle here but yeah, should be fixed.
SUUUUUUUUUPER LAGGY, Those flame guys unfortunately are like lag machines, and with a spinning wheel this is like 1-2 FPS, lol.
lol, that ghost guy up there is glitched to heck, even when I got all the way up there he's no better.
I felt there should've been a reward/secret for getting all the way up here.
Glitched sprite here, assuming you knew about this?
BTW I am not sure what your plans are for the boss arena but I did hack the Boo boss and I'd like to use it here. You can change the arena around however you want but let me know if you'd like the ASM patch so you can see how he will be.