Reading a lot on motivation…. a lot is written and researched on in educational context, not so much in behavior change yet, or did not find it yet.
Another thing which might be mentioned…. who tried to create/design a book which a person who does not like te read wants to read? We should take in account that people who do not like (or want) to play, or have certain preferences, might never be (made) motivated to use a game, since freedom is important to be labelled ‘play’ or ‘game’.