Agriculture is considered today as having major impacts on water quality in river basins. Transition from this situation to a better integration of agricultural practices in their environment is sought by many stakeholders and policy makers, from water, land development and also agriculture sectors. This appears costly when incorporating their various constraints. With the on-going research project ExpEau, the LTSER-FR network aims at (1) raising awareness on the opportunities to handle agricultural sources of water pollution collectively, and (2) comparing them in various watersheds. To that end, we are developing a hybrid serious game featuring activities and relations between farmers, municipalities and river basin organization on a virtual river basin, generated from actual datasets for topography, soil properties, and climate. For comparison sake, the game features a framed number of entities and possibilities of action, and the process of transforming actual datasets is standardized. We consider representative small basins (ca. 100 km2) that we discretize into three sub-basins, each of them representing a municipality as the first level for collaboration. Each sub basin counts about 30 hexagons elementary tiles with a single land use for each. In practice, the game is made of a physical board and playing action cards, as well as a twin on-line version. Farmer players access to the information on their environment and choose cultural practices thanks to a smartphone. Municipality and river basin organisation roles use their time and budget to facilitate collaboration and support more virtuous practices as well as infrastructures to decrease pollution. A local server computes the impacts of these actions in terms of production, collective well- being and contamination, and updates the players’ data. During the game session, players can see the virtual watershed, the land use and the infrastructures on the physical board. According to their role, they receive situated information on production, on territorial well-being and water quality and quantity. Involving students or local stakeholders, each session is followed by a debriefing that could produce (1) a local understanding on the interactions between agriculture and water quality, and (2) socio- ecosystem data to feed a cross LTSER analysis of these interactions.