A good portion of my philosophy of game design came from many years of teaching game development and two key textbooks. The first textbook is Rules of Play by Eric Zimmerman and Katie Salen, published in 2003. This book provides an in-depth and thorough coverage of games, game history, and game design. The other book that heavily influenced me was Half-real by Jesper Juul, published in 2005. This book offers a more concise study of game design. If you have a passion for game design, I highly recommend that you read these two books.