Salt intrusion is a growing problem in many deltas around the world. During periods with low river discharges, salinity upstream in a delta increases and affects freshwater availability, ecology, and other delta functions. For example, in the Rhine-Meuse estuary (the Netherlands), brackish water can reach drinking water intakes about 40 km from the estuary mouth during droughts. Salt intrusion is likely to become more severe in the context of climate change, as a result of sea level rise and a lower river discharge during droughts. The challenges with salt intrusion for the Netherlands are addressed in the Salti Solutions research program. Within this program the Delta Management Game offers an interactive environment where policy-making stakeholders can experience salt intrusion management and experiment with adaptation and mitigation strategies in the Rhine-Meuse estuary. As a serious game, the goal is for players to “learn by taking actions and by experiencing their effects through feedback mechanisms that are deliberately built into and around the game” (Mayer, 2009, p. 825). A particular design challenge for serious games is simplifying the environmental system and sufficiently representing the relevant physics, while offering exploratory and experimentation through (near-)instant, interactive feedback. The physical module for salt intrusion in the Delta Management Game should be able to deal with, among others, changes in bathymetry (e.g. depth or width of waterways, adding a sill) of the estuary in the game, while offering relatively quick feedback. @en