Abstract Background This exploratory study engaged teams of elementary and middle school students in the collaborative design of digital games. Game design is theoretically examined in this study as a form of knowledge-creating learning that is characterized by collaborative efforts to advance a shared object of activity, i.e., the game being designed. Using mixed methods, we examined how students experienced the game design project and how the project fostered connected learning, that is, integration of students’ personal interests and supportive peer relations with their schoolwork, and how their self-assessed digital competences developed. Methods The digital competences of 98 comprehensive school students across Finland were traced using pre- and post-questionnaires. The post-questionnaire also included validated measures on connected learning. Quantitative methods were used to analyze structured measures, and qualitative methods were used to analyze open-ended measures. Findings Students experienced game design as an inspiring, challenging activity. Game design engaged student teams in sustained, collaborative efforts to create shared digital artifacts. Their efforts involved a great deal of mutual support and knowledge sharing. Participation also improved students’ self-reported technical and artistic digital competences. The game design project fostered informal, interest-driven, sociodigital participation; inspired learning engagement; and improved schoolwork practices. Contribution The game design project appeared to be a pedagogically meaningful way of engaging students in knowledge-creating learning and of connecting students' formal and informal learning. The project sparked students’ motivation to learn, fostered digital competences, and enriched the learning environment.