Games are of interest for health interventions including but not limited to physical activity and rehabilitation, behavior change, motor-cognitive training, and mood elevation. Despite increased interest in using games to produce positive health outcomes, the development or selection process of games, or their suitability for a target demographic in a context of health and rehabilitation, remains ad-hoc. As a result, game-based interventions lacking application specificity produce variable outcomes that obscure the true treatment effect of game-based therapies. To address this issue, we present a design strategy for game-based rehabilitation that uses a player-centric approach to develop/select games for specific contexts such as for improving functional deficits in patients with Parkinson's disease. This strategy establishes a relationship between the exercise rehabilitation regimen and gameplay by incorporating the rehabilitation requirements, patient condition, and player affordances, into the game world. In addition, we present guiding questions to support the application of the design strategy for improving the effectiveness of game-based rehabilitations.