This paper relates to an empirical study about the use of a Game-Based Learning approach for Sustainable Development Education. We de signed Clim@ction, an online multiplayer game which aims at fostering epistemic interactions between French and Canadian secondary students that are involved in designing an innovative project for the implementation of “Green” energy. The study aims at addressing the following questions: How to design a realistic situation which allows the students to be engaged as citizens and to grasp the complexity of the world? Which elements should be taken into account for the game design in order to permit the learner/gamer to be engaged in epistemic activities? The digital records of students’ interactions with the digital platform permits to draw an epistemic models of students (Wenger, 1987). The data collected during the study include as well the recording of the teachers during the focus groups dedicated to the design of the game and the recording of the students after the game session. Our preliminary results permit to identify several key factors that should be taken into account in order to foster epistemic
interactions between students.