How should we understand and design for fun as a User Experience? This new edition of a classic book is for students, designers and researchers who want to deepen their understanding of fun in the context of HCI. The 2003 edition was the first book to do this and has been influential in broadening the field. It is the most downloaded book in the Springer HCI Series. This edition adds 14 new chapters that go well beyond the topics considered in 2003. New chapter topics include: online dating, interactive rides, wellbeing, somaesthetics, design fiction, critical design and participatory design methods. The first edition chapters are also reprinted, with new notes by their authors setting the context in which the 2003 chapter was written and explaining the developments since then. Taken with the new chapters this adds up to a total of 35 theoretical and practical chapters written by the most influential thinkers from academia and industry in this field.