Adverse Childhood Experiences (ACEs) significantly impact youth mental health, yet stigma and limited service capacity prevent many young people from accessing care and support. Serious games offer an engaging medium that interests young people through play, and there is emerging evidence of effectiveness for adolescent mental health. This paper describes the design and development of ACE of Hearts, a serious digital game designed to support young people affected by ACEs. Employing an iterative, experience-based co-design (EBCD) approach involving young people and stakeholders, the game creatively integrates metaphorical storytelling and early elements of Narrative Exposure Therapy (NET), providing information and self-directed space for reflection and narration of young people’s predicaments. The prototype includes a central cozy space and four mini-games, each addressing distinct combinations of ACEs, including sibling caregiving and bereavement, disability and trauma, gender dysphoria, and poverty. These issues were designed into the serious game through multimodal storytelling and interactive metaphors. We considered ethical safeguarding and user feedback and highlight the implications for future research.