Background <p>Adolescents in Denmark increasingly report poor mental wellbeing and health behaviour. Additionally, they spend less time being physically active and being with friends and more time on gaming and social media. The eHOOD intervention was developed to address physical and mental wellbeing of adolescents in vulnerable positions using their motivation for gaming to engage them in a community entailing physical and social activity, and education with peers. This study aimed to assess the evaluability of the eHOOD intervention, to develop an evaluation design, and to test the feasibility and acceptability of the evaluation design and the intervention.</p> Methods <p>Evaluability assessment was performed by a working group in a series of workshop-style meetings involving a literature review, creation of a theory of change, and preparation of an evaluation plan including outcome measures, instruments, and data collection procedures. Subsequently the evaluation design and the intervention were tested in a single arm feasibility study. Participants were 13 adolescents aged 13–16 years. The participants met with a coach and a local pedagogue in an after-school club four hours a week for 25 weeks practicing gaming, engaging in physical and social activities, and learning about healthy lifestyle habits through education and communal cooking and dining.</p> <p>Feasibility and acceptability of outcome measures, instruments, and data collection procedures were assessed, and initial changes in outcome measures were measured. Recruitment and retainment of participants were monitored, and participants’ motivation for and benefits of participating were explored. Data were collected with qualitative and quantitative methods.</p> Results <p>An evaluation plan was developed and found to be suitable for use in the subsequent feasibility study. The evaluation design was overall feasible and acceptable, although several important adjustments to measurements and data collection procedures were identified. Initial changes in wellbeing were observed and the World Health Organization-Five Well-Being Index (WHO-5) was deemed relevant as a primary outcome in future evaluation. The intervention was found feasible and acceptable among participants in the present format.</p> Conclusions <p>This combined evaluability assessment and feasibility study suggests that the eHOOD intervention is ready for larger-scale evaluation, although refinements to outcome measures and data collection procedures are warranted before effectiveness can be evaluated.</p> Trial registration <p>ClinicalTrials.gov, March 23, 2026. Identifier NCT07489365. Retrospectively registered.</p>