This study investigated the knowledge gains and attitude shifts attributable to a unique online science education game, "Uncommon Scents." The game was developed to teach middle school students about the biological consequences of exposure to toxic chemicals in an environmental science context, as well as the risks associated with abusing these chemicals as inhalants. Middle school students (n = 444) grades six through eight participated in the study consisting of a pre-test, three game-play sessions, and a delayed post-test. After playing the game, students demonstrated significant gains in science content knowledge, with game usability ratings emerging as the strongest predictor of post-test content knowledge scores. The intervention also resulted in a shift to more negative attitudes toward inhalants, with the most negative shift occurring among eighth grade students and post-test knowledge gains as the strongest predictor of attitude change across all grade levels. These findings suggest that the environmental science approach used in "Uncommon Scents" is an efficacious strategy for delivering both basic science content and influencing perceived harm relating to the inhalation of toxic chemicals from common household products. (Contains 4 tables and 2 figures.)