Video games are learning machines. Serious games are games that attempt to impart knowledge and skills that can be used in everyday life while taking advantage of the game mechanics used in commercial games to keep player engaged, to get the player to learn new skills and to enjoy learning for hours at end. The aim of this project is to extend and adapt current computational models of argumentation to support the range of user actions and diverse scenarios in serious games; test and evaluate the effectiveness of the argumentation model in changing people's behaviour and decision through gameplay; and develop tools for game designers to explicitly model player reasoning enabling richer and more adaptive interactive environments.