The empirical study, in this article, involved 42 students (ages 14-15), who used the urban simulation computer game SimCity 4 to create models of sustainable future cities. The aim was to explore in what ways the simulated "real" worlds provided by this game could be a potential facilitator for science learning contexts. The topic investigated is in what way interactions in this gaming environment, and reflections about these interactions, can form a context where the students deal with real world problems, and where they can contextualise and apply their scientific knowledge. Focus group interviews and video recordings were used to gather data on students' reflections on their cities, and on sustainable development. The findings indicate that SimCity 4 actually contributes to creating meaningful educational situations in science classrooms, and that computer games can constitute an important artefact that may facilitate contextualisation and make students' use of science concepts and theories more explicit.