The popularity of games as educational tools has steadily increased and is mainly explained by the motivational power that is ascribed to games in general. The research investigates the role of different motivational forms in educational gaming and the influence of game and teaching context on the students' motivation to involve in game play. Based on self-determination theory and a mixed-method case study approach, seven educational games played in a postgraduate level engineering course in two consecutive years were studied. Our research reveals that different motivational forms can co-exist when students play games and that the interplay of game attractiveness, game learning and game operativeness can explain the emergence of these motivational forms.