The urban sustainability transformations that are urgently needed will have significant effects on the daily lives of city dwellers. As ways to imagine and co-design sustainable urban futures, experiments within the present-day urban environment are increasingly popular. This paper investigates how such an experimental approach can serve as the base of an applied urban futures game that enables its players to reflect on and imagine ways to address complex sustainability problems. We developed a large-scale mobile urban futures game, Utrecht2040, that provides its players with sustainability content, reflection, and motivation for action. The digital infrastructure of the game and large number of players provided unique opportunities for measuring outcomes. Our results indicate that this type of experimental gaming offers a new way for players to collect existing sustainable practices or ‘seeds’, and use them to collectively create glimpses into relevant sustainable urban futures. At the individual player level participants reported an increased understanding of sustainability and motivation to act. We conclude that large-scale collective experimental futures games in socio-spatial urban environments are a high-potential avenue for overcoming the “crisis of the imagination” by creating inclusive urban futures that inspire action.
