ad physics: Thanks. I believe even more "types" of jump can be set with the current model if the play area was bigger. One idea was to have some collectibles which upgrade your max momentum – thus making some sort of metroidvania with keys blocking future area, allowing you to cross gaps you used to not be able to..
But I was outright scared switching to a smaller tilesize (say, half the current one) as I was unsure how well collision detection would fare if size of tile was odd. Also, block placement is via coords instead of having 2D char map which would be tiresome to convert to the new tilesize.
ad music: Yay for finally getting to adding music/sound into any gosu project. Next time it should thus not look like a such a hurdle and can be done much more quickly.