Childhood obesity in Portugal (29.6%) demands innovative interventions integrating school, family, and local governance. Loopalot is a gamified digital educational multiverse to promote nutrition literacy and physical activity in primary school children. This project will develop and test Loopalot through three phases: (1) Participatory co-design with children, teachers, families, and municipal decision-makers from Valongo (workshops to co-create content, game mechanics, and dashboards); (2) Prototype development with 5 functional digital missions; (3) Usability testing in 1 school (n=20-30, 5 sessions) evaluating technical functionality, acceptability, and engagement (not behavioral efficacy). Using mixed methods (observations, questionnaires, interviews, digital logs), the study will produce a validated prototype and technical specifications for full development.