Human decision-making plays a critical and challenging role in the prevention and control of public bads within socio-ecological systems. Farmers daily confront dilemmas regarding public bad management, such as infectious diseases in their crops. Their decisions interplay with multiple factors and may create the risk conditions in which a public bad can occur (e.g., a disease outbreak). This article presents an experimental board game method (DySE) and its contextualized version (Musa-game) to study the effect of individual and collective human actions on creating or prevent-ing a public bad. The DySE method and the Musa-game add emergence and spatiality (both attrib-utes of SES) to the study of public bads and collective action problems. This methodological pro-posal allows us to build a contextual understanding of how individual and collective actions of various entities lead to typical system outcomes, i.e., conditions that are (un)favourable to patho-gens, and individual decisions about infectious disease management. To conceptualize our method, we used the case of Banana Xanthomonas Wilt disease in Rwanda. This research is published as a diptych. Part I (this article) covers the conceptualization and design of Musa-game. Part II presents empirical findings from testing Musa-game with farmers in Rwanda and recommendations for using the method.