The Guardians: Designing a Game for Long-term Engagement with Mental Health Therapy

This work introduces The Guardians: Unite the Realms, a novel free-to-play and publicly released mobile game that encourages the adoption of healthy real-world behaviours in exchange for rewards that enrich the gaming experience. We describe the game, its grounding in a mental health therapy known as behavioural activation, and how we designed it to keep players engaged over time. Instead of using traditional digital health gamification techniques such as badges or leaderboards, The Guardians creates a motivational pull by embedding the therapy into a complete mobile game. In-game items earned via the therapy have an immediate purpose in the game and, thus, they are considered intrinsically valuable by players. Analysis of game interaction data from 7,782 real-world users suggests 15-day and 30-day retention rates of 10.0% and 6.6%, respectively, which is more than double the average retention levels of most digital mental health interventions. Furthermore, players reported completion of a healthy real-world task on 69.0% of days played (37,574 completed tasks in 54,461 total days). We also report interaction metrics with game features and the effectiveness of the players' chosen real-world activities.