Despite the traditional opposition between play and work, games and their structure are increasingly used in workplaces. This phenomenon of using game elements or mechanisms in other contexts than games is named ?gamification?. In workplaces, the gamification is supposed to abolish the separation between work and leisure or between constraint and pleasure. This book reviews a century of game theories in the social sciences and analyzes the uses of games in workplaces. We critically question the explicit functions (learning, experimentation...) which are supposed to be conveyed by games. Finally, we show that game, understood as a structure, could have efficient social functions in the workplace.