Purpose: Knowledge Sharing (KS) is seen as a promising framework for renewing advisory systems in agriculture, but its practical application remains an important area of research. In particular, it is important to increase the motivation of farmers to participate in decision-making. Game-based support seems to be applicable to a long-term process of KS. Approach: The authors spent one year developing a methodology to help identify a common vision among multiple stakeholders in a PDO area. This area of cheese production (Fourme de Montbrison) faces important difficulties with sustainability issues and a very low degree of farmer participation. The methodology is based on game learning and incorporates three phases and six steps and is centred on two serious games. Findings: Results present an analysis of the farmers’ participation and the common vision for the future that the game-based methodology enabled us to identify. The games facilitated the farmers’ implication in collective decision-making and their continued engagement afterwards. Practical implications: the article discusses the advantages of the game-based methodology, such as involving local knowledge of farmers at all stages and encouraging their long-term engagement in collective decision-making. Theoretical implications: the article complements the existing scientific literature on KS by emphasizing the importance of long-term perspectives in a game-based learning approach. From a socio-constructivist perspective, it also highlights the potential of game-based learning to motivate farmers in collective decision-making. Originality/value: This support methodology could be a source of inspiration for extension actors facing similar development problems and the revitalization of their role as facilitators.