Technology-based interventions for promoting health behavior-change frequently leverage multiplayer game mechanics such as group-based competitions. However, health interventions successful for groups writ large may not always translate to successful behavior change at the individual level. In this paper, we explore the tension between group and individual success, based on an empirical study on a long-term real-world deployment of a pervasive health game for youth. We report five distinctive player types along the dimensions of motivation, behavior, and influence on others. Based on the findings, we provide design suggestions to help game designers integrate group-based mechanisms that maximize intervention effectiveness.