The more I get into game design, the more pleasantly surprised I am at how much psychology is involved. If you think about it, game designers shape experiences, so they must constantly dig into their toolbox of psychological principles.
If you’ve ever played a game and striven to attain any of its achievements (think Angry Birds), the game designers have hooked you in with psychology. Achievements, like visual feedback, audio, and various missions and challenges, play a huge part in the perceived fun and replayability of a game by motivating players.
To learn more, take a look at this article on how to design effective game achievements: The Cake Is Not a Lie: How to Design Effective Achievements