21st century education is challenged to provide individuation, self-direction, and applicability to practical life situations. Responses include learning by doing, learning by making, and learning by teaching, and also rethinking education as a process of being and becoming. Game based learning is presented as a complement or alternative to traditional formal education, highlighting engagement, which can be broken into presence, agency, and identity. This paper proposes a system for fostering and regulating mastery of applied concepts, skills, and attitudes through integrating learning (by doing, making, teaching, and being and becoming) into the play of an online game, and through integrating the usually peripheral or separated community and development activities associated with such games into the game experience itself. The system scaffolds a progression of learning and taking on roles, from player, to builder, to manager, developing productive and metacognitive capacities, and a game system that is self-sustaining, self-generating, and open-ended. [ABSTRACT FROM PUBLISHER]