Mobile games are based on the physical movement of players in a game world, combining real world with virtual dimensions. As the real world defies control, the magic circle, the border of the game world, becomes permeable for influences of everyday life. Neither the players nor the designers nor the researchers are able to foresee and fully control the consequences of players' actions in this world. In our paper we introduce a case study. Within this empirical study the difference between the game as a system on the one hand and the context of play on the other hand becomes discernable as a source of emergent game play. We then elaborate on its meaning for the process-oriented method.