Gamification, the application of game design principles to a non-gaming context, has been used to promote pro-environmental behaviors. Such principles have been implemented in boardgames, team competitions, electronic games, smartphone apps, and in apps that researchers developed primarily to collect data. We review the games and apps that have been evaluated in empirical research in the last 5 years and provide a list of apps and games that have yet to be tested. Gamification has been used for sustainability education, energy reduction, transportation, air quality, waste management, and water conservation. Although we do not know yet why certain games and apps are more effective than others, gamification appears to be a promising avenue for preventing climate change.