I was originally planning on doing the music composition, but the texture and level design budget took a lot of time away. So, instead, I focused on getting authentic ambiance/sound effects. I definitely do think music would be a good fit, maybe one different track per dungeon.
As for the ending, I think it might surprise you. The dungeons themselves were designed to trick the player into thinking they were fulfilling the theme, but there's a shocker at the end that reveals the true lie.