The research approaches civic engagement from the perspective of Intermedial Studies, shedding light on different strategies of ‘mediation’, the way people engage in civic practices and shape the public sphere in postdigital culture. The paper explores the evolution of civic webs, living labs, forms of meaningful play in ludified transmedia practices, and serious videogames as diverse media that can address the intersection of civic engagement and sustainable development. A focal point of the research is the role of intermedial participatory strategies to promote a sociocultural scenario sensitive towards United Nations' Sustainable Development Goals (SDGs) related to urban planning, smart cities, and environmental issues. Building upon this starting point, the study extends to the transformative realms of transmedia storytelling and the difference between ludification and gamification, elucidating the main role of game-based public participation to fostering community engagement and eco-digital literacy. The paper supports the empowering potential of multiplatform, co-creative and experimental environments in advancing communal pursuits of sustainable goals in interconnected and offline contexts for sociocultural innovation.