A must-read for every game designers, wannabe or seasoned.

Simple, accessible and funny, the author succeeds in an also impossible task: to make understandable something concerning lots of different research fields.
Through clear examples and solid demonstrations, he explains and dissects what makes (video) games fun, and how recreate it.

A lot more concise than some others on the subject (like Rules of Play: Game Design Fundamentals), while still complete about its subject, this book is the perfect complement to The Art of Game Design: A Book of Lenses, for a more theoric approach.