I really enjoyed this update; I think you totally nailed the chapter 2 cave feel. Perfect ambiance, and the boss music is SO GOOD! Unfortunately, the game crashed every time the bat took flight (Linux version!). Not the bat boss, but the 1st stage bat, making it impossible to progress. Thankfully, I remembered the map change command from a few versions back, which allowed me to enjoy the update. I love the new boss, character, and especially the final boss area, plus the music! It totally lets you immerse yourself in the fight, and its upbeat tones once you defeat the boss are just so rewarding. I love how this game is turning out and cannot wait for the next update!
P.S. Thanks for adding a difficulty setting! The game felt just a tad bit hard for me, so this is a welcome change!