Augmented reality(external) (AR) games such as location-based games add virtual content on top of the real world. We investigate why playing these games feels meaningful to players by focusing on the dimensions of imagination and sociality. We theorise a structural model that we test with data collected from a global sample of players of the popular AR game Pokémon GO (N = 515). Our findings show that nostalgic feelings about Pokémon increased imagining AR content in the real world. Surprisingly, using imagination in this way was a much stronger predictor of affection towards the fictional pokémon creatures than nostalgia(external). The affection towards the fictional creatures, in turn, increased the meaningfulness of playing. Regarding the social factors, community identification and social self-efficacy increased players' sense of meaningfulness of playing. As our study's main design implications, we highlight the importance of socially shared narratives and harnessing the players' imagination to support a sense of meaningfulness of playing.