Thanks, I'm glad you liked it! I watched a lot of videos on Metroidvania games (specifically Metroid and Alwa's Awakening) to try to get the idea down. I do love the GameBoy aesthetic, mainly because it limits me and makes me weirdly nostalgic for games I didn't play until college (only a few years ago). I wish I had time to create my own music for the game, but definitely some great creators out there who let you borrow their stuff.
As for going back to the beginning, were you able to save at the checkpoints? There is a save system, but wasn't sure how well it works beyond my debug build. I didn't really get a chance to test it.