Games are a unique art form. They do not just tell stories, nor are they simply conceptual art. They are the art form that works in the medium of agency. Game designers tell us who to be in games and what to care about; they designate the player's in-game abilities and motivations. In other words, designers create alternate agencies, and players submerge themselves in those agencies. Games let us explore alternate forms of agency. The fact that we play games demonstrates something remarkable about the nature of our own agency: we are capable of incredible fluidity with our own motivations and rationality. This volume presents a new theory of games which insists on games' unique value in human life. C. Thi Nguyen argues that games are an integral part of how we become mature, free people. Bridging aesthetics and practical reasoning, he gives an account of the special motivational structure involved in playing games. We can pursue goals, not for their own value, but for the sake of the struggle. Playing games involves a motivational inversion from normal life, and the fact that we can engage in this motivational inversion lets us use games to experience forms of agency we might never have developed on our own. Games, then, are a special medium for communication. They are the technology that allows us to write down and transmit forms of agency. Thus, the body of games forms a "library of agency" which we can use to help develop our freedom and autonomy. Nguyen also presents a new theory of the aesthetics of games. Games sculpt our practical activities, allowing us to experience the beauty of our own actions and reasoning. They are unlike traditional artworks in that they are designed to sculpt activities - and to promote their players' aesthetic appreciation of their own activity.