This study is a qualitative exploration into the roles and social identities that Research Engineering Undergraduates (REU) enacted while engaging the public through designing serious games. At present, the science communication field is searching for ways to train the next generation of scientists to practice public engagement with science in a way that fosters dialogue with the public, however, little research has been done on training undergraduates in this regard. This exploratory study seeks to determine what opportunities a game design project in a summer program in solar energy engineering research provides undergraduates to that end. The project includes REUs designing games through a facilitated design process and then sharing them with the public at arts festivals. Through discourse analysis, data was analyzed through the lens of cohesion in order to interpret what roles and social identities REUs enacted as well as members of the public who play the games. Based on the analysis of 12 REUs and 39 player participants, findings indicate REUs most often enacted the science game designer social identity and science educator role during the public event. Less often, REUs enacted a sociotechnical role to determine the player's relationship to science/solar energy. Also, less often did they position themselves directly as scientists. For the most part, REUs reproduced the dissemination model of science communication in an interactive way and with an element of reflexivity. However, during public engagement events, dialogue with the public occurred when REUs enacted open-ended roles that enabled members of the public to contribute to the conversation by assuming a range of roles and social identities rather than positioning them into a single role. Dialogue was also supported when REUs were responsive and shifted their role/ social identity to correspond with the public’s enactment. Some players enacted a local Arizonan social identity in response to the open-ended role and game content about Arizona’s solar energy. The project afforded REUs the opportunity to learn illustration and reformulation to communicate science concepts. Also, REUs referenced their game during illustration and reformulation, using it as a tool to teach science, be a science game designer, and other enactments. More research is needed to determine how science, technology, engineering, and math (STEM) undergraduates learning science communication can design serious games and conduct player reflections in such a way to promote dialogue to a greater degree than observed in this study.