This study examines gender differences in affective outcomes, gameplay behaviors, and perceptions of gameplay of fifth to eighth grade students who played an exhibit-based mobile game during a group field trip to a hands-on science center. This mixed-method, quasi-experimental study used a pre-/post- administration of the Motivation to Learn Science Questionnaire, first-person GoPro video, and follow-up interviews. Results indicated that girls had higher science self-efficacy before their visit to the science center and outperformed boys on every measure of game achievement. The content of the qualitative data suggested that Lazzaro’s 4-Keys to Fun (2004) was a good fit framework for describing participants’ behaviors and perceptions of the game and visit to the science center. Data revealed that girls tended to be more goal-oriented, persistent in the face of difficulty, and appreciative of “hard fun”. However, gender differences in science self-efficacy did not exist on the post-measure.