This report summarises the outcomes of the GAMEHEARTS Design Thinking Marathons (GH DTthons), which explored new pathways for effective cooperation between the European Video Game Industry Ecosystem (EVGIE) and the other Cultural and Creative Industries (CCIs). In particular, it presents key findings and twelve idea cases illustrating actionable cooperation models, as well as strategic recommendations for policymakers and practitioners. Methodologically, the DTthons represent an innovative, participatory research format that combines scientific inquiry with practical co-creation. The study involved 72 practitioners from across Europe, including game developers, cultural organisations, creative industries, academia, and policymakers. It demonstrates that, with appropriate facilitation and systemic support, cross-industry cooperation can become a powerful driver of European competitiveness, cultural vitality, and social cohesion.