You killed it!!
even the bass seems to have a harmonic overtone melody. Didn't realize the potential of chiptune. At first i thought zelda for gameboy advanced, and then scope broadened as the music started to go through variations in sound pallete. and i say sound pallete because what you did seems more like sound design then stock instruments. The sounds designed indicated a scene change for me, but all still in the crystal castle, so not straying to far from the main theme. Just variations on the main theme. Mario 64 could have learned a lot from the coherence displayed in this one song. Well done!