This paper adds to the small but growing body of research into the potential of augmented reality games for teaching and learning English as a foreign language (EFL). It explores the extent to which such games enhance the language learning experience of advanced level EFL learners. The author draws on his work developing "Mission not really Impossible," a location-based augmented reality game which uses the Aurasma mobile application to provide a series of challenging language tasks for advanced level learners as they move around the city of Karlsruhe in Germany. The game is evaluated through a mix of observation during gameplay and feedback from participants. Broad approval of the language challenges that had to be completed is evident and Aurasma proves itself to be user-friendly and reliable. The findings affirm the potential of augmented reality games to engage and challenge advanced level language learners.