“Doors” is a book from famous American illustrator and writer Roxie Munro. It has received numerous recommendations and awards. “Doors” is a lift-the-flap book with hidden objects. Behind doors, cupboards, train interiors, the space station, sailboats, and other spaces are objects you can find and worlds to explore. There are more than 50 flaps to check out and to look behind. We thought “Doors” would make a great app, with a lot of extra possibilities and interactivity. But it is going to be a tedious and difficult task. We analyzed each page carefully, decided what we could do with it and how we were going to do it.