Objective: Although some serious games have been developed for physical therapy, little work has been conducted through a participatory design approach. Therefore, a game prototype was developed, which involved related stakeholders in the design process. Materials and Methods: The iterative participatory design process was adopted with the input of 18 patients with frozen shoulder symptoms, 4 health professionals, 2 game designers, and 5 researchers in an iterative process to design, test, and evaluate the game prototype. In total, 17 patients participated in the interviews to explore their needs and desires for a serious game. The health professionals participated in the interviews to understand the medical requirement and experience pertaining to frozen shoulder and were included in the workshop to give feedback on the game prototype. At the conclusion of the iterative design process, a Kinect-based prototype game with three levels was used for a case study with one patient who was diagnosed with frozen shoulder and has been receiving medical treatment in the hospital. Results: Based on the outcomes derived from data collected among diverse stakeholders, the prototype game underwent iterative development by the team and was assessed by a participant with frozen shoulder symptoms. Findings revealed that the participant demonstrated enhanced shoulder mobility and a reduction in pain intensity, despite the lack of significant improvement for health-related quality of life. Nevertheless, the participant reported a positive experience with the prototype game. Conclusion: This study underscores the importance of involving diverse stakeholders in the development process to create more effective and user-centric serious games for rehabilitation. The participatory approach, exemplified by the prototype game, demonstrates potential improvements in both user experience and overall effectiveness during the rehabilitation process.