Creativity has been of research interest to psychologists dating back many decades, and is currently recognized as one of the essential skills needed to succeed in our complex, interconnected world. One medium that has affordances to assess and support creativity in young people is video games. In this paper, we briefly discuss the literature on video games and creativity and provide an example of current work being done relative to measuring creativity in the context of a game called "Physics Playground" using stealth assessment. To validate the stealth assessment of creativity, we conducted a one-group pretest-posttest study with 167 8th and 9th graders from a K-12 school in Florida. Results suggest that our stealth assessment of creativity is valid (i.e., our stealth assessment estimate significantly correlated with our external performance-based measures of creativity). Additional analyses revealed that creativity (i.e., estimated using our stealth assessment of creativity) significantly predicts in-game performance (e.g., number of levels solved), game enjoyment, and learning of physics content. We conclude with a discussion of future directions in this line of creativity research.