Isbister, K., & Schaffer, N. (2008). Game usability: Advancing the player experience. San Francisco: Morgan Kaufmann.
This is an excellent set of essays about all aspects of the game experience. Despite the book's title, the analysis ranges far beyond "usability" but includes all aspects of research during the development of a game, with special attention to the experience being generated by the people playing the game. There are 23 chapters covering a wide range of topics and approaches.
Randy Pagulayan and Dennis Wixon's Foreword describe the challenges nicely: "the next evolution in games research will be .. focusing less on cognitive states and emotional taxonomies, and more on opportunities for player behaviors. Games can become complete worlds for our users, so now more that ever we need to understand the interactions between the player and the environment, understand the player's behavior within a virtual world, and understand the player's ability to detect the infinite possibilities created for them." (Page x). Well said.
Even if you are not a game developer, this book should be part of your arsenal: everything we design, everything we build, should incorporate fun, delight, exploration, and surprise. Our devices become part of our lives, not just virtual worlds, but real worlds. Game developers learn through understanding how people interact with the real world: Application developers learn by understanding how people interact within game worlds.