Background: Educational video games are increasingly used in classrooms because they can offer meaningful contexts for problem solving. However, educational video games bring together two historically disparate activities: school mathematics and video games. How these two activities complement, compromise, or contradict each other influences how mathematical activity takes shape during game play. Methods: This paper offers a case analysis of two students: one who engages with the mathematics as intended by the game and is easily seen as on task, and a second who seems to reject the mathematics as intended by the game and is easily seen as off task. The analysis focuses on how each student's frame of activity influences their mathematical activity during game play. Findings: Findings suggest that, considered from their own frame of activity instead of the frame of the design, both students appear engaged in mathematical sensemaking, albeit in different ways: one as intended by the designer, the other as emerging from game play. Contribution: By highlighting potential tensions between these official and unofficial frames, this paper contributes to continued reflections on task designs that incorporate youth culture such as video gaming to make mathematics classrooms more inviting to students.