Wow, this is really clever! At first I was thinking, "what is this? Why is there a story?" ...but if you stick with it it's very, very good. You're a very gifted illustrator and storyteller. I actually thought you borrowed the illustrations from a storybook. If things don't work out with the app you may have a future as a children's author. In fact, maybe you could publish a book version of this as a companion to the app?

I wonder if the entire experience would be better if the entire UI for the walkthrough at the beginning was the storybook without the shelf(?) and the black background, then after the story is at the end make the "last page" a fullscreen app?

The dark colors and the image mirroring was distracting and it isn't clear what its purpose is until the screen rotates, which is a very cool effect. I wonder if there's a way to achieve the same effect without rotating the screen though.

That said, an app for building habits is something I've thought about before, and I think your execution and creativity is way better than anything I would've imagined. Gamification feels like a needed component, but I wouldn't have thought of this. It almost feels like Legend of Zelda for self improvement!