The use of games in therapy has become popular in recent years due to their ability to engage young patients, particularly children and adolescents who struggle with traditional treatment (face-to-face treatment). In addition, games can provide a structured and engaging way for therapists to help clients develop new skills, work through challenges, and build positive relationships. However, limited guidelines exist for designing a therapeutic game for mental illnesses. Thus, this study proposed a design model named Cognitive Behavior Therapy-Therapeutic Game Design Model, or short called CBT-TGDM. An expert review was utilised to validate the proposed model. Based on the findings, it was found that CBT-TGDM can be used to guide the design of therapeutic games for adolescents with depression. The results also indicate the importance of adopting a relevant therapeutic model in designing game health.