Just popped in to report the escape room bug, but it's already been reported. (Loving the game btw)
I'd personally love that kind of streak system that makes dungeons a little harder each time you win consecutively (definitely make it reset to 21 when you lose though). Something as simple as -1 max hp per consecutive dungeon-win, like you mentioned, would be great for replay value. It would obviously get impossible at a certain point, but that only adds to the excitement when you getting lucky and survive at very low health.
*edit* While I'm here, a fullscreen option would be nice. The game window is very small.