I’m working on the second floor now (and trying to decide where I should make the next cut-off point for an updated demo).
Along the lines of what @Aera was suggesting with secrets and items with special properties, I’ve added a plant to the second floor that the player can attempt to save by regularly watering it across the course of the game. It’s entirely optional, and it never tells you what the benefit might be…
…but there is one.