This study builds on a previous umbrella review that highlighted the effectiveness of combining Extended Reality (XR) and Game-Based Interventions (GBI) in mental health treatment, showing positive results in reducing anxiety, depression, and stress. XR included augmented, virtual, and mixed reality, while GBI encompassed serious games, gamification, game-based learning and training, exergames, and commercial video games. The review analyzed 201 studies and selected 16 (nine meta-analyses, six systematic reviews, and one scoping review). Given the role of design in digital mental health solutions, here, we conducted a reverse engineering analysis to understand how these interventions worked by reviewing descriptions and visual representations from each study, breaking down XR-GBI into core game elements. This allowed us to identify design features and motivational purposes linked to their effectiveness, as well as underused elements to inform future research and innovation. Frequently used game elements included 'Emotions', 'Single-player', 'Consequence', 'Simulation', 'Customization', 'Meaning', 'Level', 'Exploration', 'Narrative', and 'Feedback'. The knowledge of frequent and underused game elements offers insights to advance XR-GBI design knowledge and support their use in digital mental health to boost intrinsic motivation, supporting cognitive and behavioral change. However, the absence of multiplayer features reveals a research gap, suggesting XR-GBI could be improved by adding cooperative, competitive, or collaborative elements. Future research and interventions should build on the game elements identified here to enhance mental health outcomes while exploring new elements, particularly social dynamics, to strengthen engagement and therapeutic impact.

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Anxiety,Depression,Extended reality,Game,Mental health,Stress