The purpose of this qualitative case study study is to examine the ways in which mobile videogames can be used in non-formal educational environments, to support students to develop decision-making skills through negotiated play. In the context of this study, the health literacy mobile videogame, PlayForward: Elm City Stories developed at Yale University was implemented in an afterschool setting in southern Europe. In this study we explored how secondary school students negotiate meaning, make decisions, and interpret the consequences in a non-formal education context, through an interpretive symbolic-interactive framework. The data included individual interviews with students, field-notes, and video-based student-groups’ interactions. These were analyzed with the use of open coding techniques. The analysis of the data resulted in the following three assertions: (a) The technical affordances of the game such as sound, usability, rating system, and visuals, are vital features that defined the quality of play and learning experience; (b) The narrative of the game guided the learning game-play experience of the students; and, (c) Students perceived that their engagement in the game facilitated their collaboration and decision-making. These are discussed alongside recommendations for game design for supporting negotiated play and decision-making.