Deception and betrayal in gameplay are generally considered off-limits, designed out of most multiplayer games. There are a few games, however, in which deception and betrayal are allowed, and even encouraged. In , Marcus Carter explores the ethics and experience of playing such games, offering detailed explorations of three games in which this kind of “dark play” is both lawful and advantageous: , , and the television series . Examining aspects of games that are often hidden, ignored, or designed away, Carter shows the appeal of playing treacherously. Carter looks at ’s notorious scammers and spies, drawing on his own extensive studies of them, and describes how treacherous play makes successful. Making a distinction between treacherous play and griefing or trolling, he examines the experiences of players to show how negative experiences can be positive in games, and a core part of their appeal. And he explains how in ’s tribal council votes, a player’s acts of betrayal can exact a cost. Then, considering these games in terms of their design, he discusses how to design for treacherous play. Carter’s account challenges the common assumptions that treacherous play is unethical, antisocial, and engaged in by bad people. He doesn’t claim that more games should feature treachery, but that examining this kind of play sheds new light on what play can be.