Nice start to a game. I like the theme and use of the constraint.
I had a hard time figuring out how to progress, even after watching the intro and reading the description. I'm not sure if this is intentional, but I was unable to destroy some of the green objects, but it still gave me progress on the ruin meter. I think it would have benefited from more feedback showing the player that they are progressing and that they've opened the cat flat (I didn't notice the meter changing until after spam clicking a book for a couple minutes). Also, a couple of the sprites seem to turn away from the user's camera rather than towards it.