The concept of intrinsic motivation lies at the heart of the user engagement created by digital games. Yet despite this, educational software has traditionally attempted to harness games as extrinsic motivation by using them as a sugar coating for learning content. This article tests the concept of intrinsic integration as a way of creating a more productive relationship between educational games and their learning content. Two studies assessed this approach by designing and evaluating an educational game called Zombie Division to teach mathematics to 7- to 11-year-olds. Study 1 examined the learning gains of 58 children who played either the intrinsic, extrinsic, or control variants of Zombie Division for 2 hr, supported by their classroom teacher. Study 2 compared time on task for the intrinsic and extrinsic variants of the game when 16 children had free choice of which game to play. The results showed that children learned more from the intrinsic version of the game under fixed time limits and spent 7 times longer playing it in free-time situations. Together, these studies offer evidence for the genuine value of an intrinsic approach for creating effective educational games. The theoretical and commercial implications of these findings are discussed
