The following books and Web sites contain in-depth information about game design.
Fullerton, T. (2008). Game Design Workshop: A playcentric approach to creating innovative games. Burlington, MA: Elsevier.
Novak, J. (2005). Game Development Essentials. Clifton Park, NY: Thomson Delmar Learning.
GameDev.net: www.gamedev.net
Institute of Play: www.instituteofplay.com
Gamasutra: The Art and Business of Making Games: www.gamasutra.com