Simulation/gaming approaches, such as participatory simulation, are commonly developed and used to support social and ecological transitions. However, the growing interest in these methods is accompanied by challenges related to evaluating and demonstrating tangible effects for potential change. Assessments often lack objective evidence and primarily rely on empirical observations. When evaluations are conducted, they tend to focus on the design itself and frequently reveal limited effects in terms of effectiveness, which are often short-term and centered on knowledge acquisition–falling short of the broader ambitions attributed to simulation/gaming. Many studies attempt to explain these outcomes in relation to the design of these methods and/or by using analytical frameworks involving numerous process and contextual variables. In this contribution, aimed at presenting ongoing research reflections that intersect literature on the evaluation of simulation/gaming and citizen participation, we explore a hypothesis centered on the design intentions of the process. This reflection is based on an analysis of the limited effects of a participatory simulation on coastal flooding risk (LittoSIM-GEN). We observe effects that are primarily short-term and focused on cognitive dimensions, which do not fully align with the initial goals of the participatory simulation. The lack of (re)definition of design intentions–concerning objectives, target audience, status and key concepts of the process–emerges as a particularly promising avenue for further exploration in our future research on the evaluation of participatory processes, such as simulation/gaming practices, aimed at supporting socio-ecological transition.