Within a context characterized by a gap between youth digital culture and university traditional habits, game-based learning is now considered as an alternative pedagogy. Serious games have the power to foster motivation and to allow the learners to face “authentic” and complex situations to develop knowledge. This paper is based on the research works of two different research teams. It aims at discussing the uses of different definitions for the expression “serious game”. We show that the choice of a definition has an important impact on the design of the game and on the knowledge assessment process.