I’m sure categorisation can occur along many different lines, but here’s one such categorisation, from Jeremy Greenfield at Publishers Weekly:

  1. Embedding a simple game like tic-tac-toe into one’s content
  2. Building in game mechanics that pull readers through the book, like a level-up aspect, where readers can earn badges or graduate levels as they progress
  3. A hybrid of the two, where the reader must engage with a game to move on in the book

– Vegetables or Candy? DBW Panel Looks at ‘Gamification’ of Children’s Books