I see what you mean with the red walls. I think I'll add an option so that people can play with the mode you describe instead if they want.
Walls feeling too thick is not something I've noticed myself or heard from other people who have played the game a lot. But the way you write about it sounds convincing. I'll experiment with reducing them and maybe make some alternate thin-wall versions of levels for people to try in the next update.
And thanks for identifying what causes the music bug, that's very helpful. Will fix.