This paper introduces the concept of sustainable serious games and discusses selected issues regarding sustainability with respect to the serious game life cycle. We take a closer look at game aging and maintenance, particularly in the context of educational serious games. We outline what aspects play into game aging and argue for the need to consider these aspects earlier in the design process. In line with the goal to outline sustainable practices in the field of serious games, we further look into the reuse of artefacts, as well as repurposing of serious games as means to create long-term value.