In this article we explore an expansion of geodesign to analyze processes of competition and cooperation by combining it with game-theoretical modelling and experiments. We test the applicability of facilitating these two fields in an integrated workshop by analysing the case study of oversupply of development sites in the Liemers corridor. Two workshops were held, with representatives of the six municipalities involved and with the regional and provincial authority, in which participants negotiated over the distribution of the supply of development sites. The workshops were performed around an interactive MapTable, with spatial information (from GIS) and financial information (from the game-theoretical model) being visualized in real-time. The integrated workshops were assessed to discover differences in terms of process and outcomes, and they examine whether and how learning takes place. We conclude that the combination of game theory and geodesign provides added value for planning support by facilitating a realistic discussion, and negotiation that is strongly connected to real-life locations, and by aiming at designing a common, collaborative solution. Through the integrated workshop learning about the problem of oversupply in financial and geographical terms and also about each otherâ€™s motives and behaviour is stimulated.