The original idea was that you would play your way through the book as a 2D platformer, progressing from page to page, with the boss fight serving as the finale. I had already finished the intro sequences, but then I ran out of time because I had some things going on in real life. So in the end, I only had enough time to make the boss fight, and even that had to be a stripped-down version.
I originally also wanted to have a proper ending where the old couple finally gets to see each other again.