Research about the effectiveness of persuasive games is still emerging. This article presents a literature review of studies that empirically evaluate the effectiveness of persuasive games. The review concluded that limited empirical evidence is currently available to prove their effectiveness in attitude change. It further revealed that almost no study employed an informative control condition, making it difficult to conclude that the game was more effective than a control condition. Next, in a pretest-posttest design an empirical study tested whether change in attitude was different for people playing the persuasive game "EnerCities" compared to a control condition where participants read a document with highly similar information. No significant differences in increase of attitude or knowledge between participants that played the game and participants in the informative control condition were found. Based on the results of the literature review and the empirical study presented, it hence cannot be concluded that playing a game leads to a greater change in attitude or knowledge acquisition than experiencing conventional media would. Future work should employ designs with proper control conditions and focus on which game features lead to significant effects.