Israeli-Jews and Palestinians cannot easily be exposed to contradicting information about “the other” in the intractable Israeli-Palestinian conflict because of the emotionally charged situation and prevailing ethnocentrism. Serious games like PeaceMaker are used as innovative interventions for peace education. Winning PeaceMaker indicates better conflict resolution skills and developing an informative viewpoint regarding the situation, which is required for conflict resolution and peacebuilding. The evaluation of the effectiveness of prosocial games in educating about conflict and peace in the literature is severely lacking. We examine the effects of this computerized simulation of the Israeli–Palestinian conflict on enhancing knowledge about the conflict and “the other” among undergraduate players who are direct parties (i.e., Israeli-Jews and Palestinians) and third parties (i.e., Americans and Cypriots). In addition, we investigate the knowledge gap between direct parties and third parties who won and did not win the game. Using questionnaires, we conducted a quasi-experimental study with 168 undergraduates using a pre- and post-intervention research design. We found that direct parties to the conflict acquired significantly more knowledge about the other side, and third parties acquired significantly more knowledge about the conflict after playing PeaceMaker. In addition, PeaceMaker minimized the knowledge gap after playing the game among direct parties who won the game and those who did not win and increased the knowledge gap between third parties who won the game and those who did not win. Our results suggest that serious games might be effective interventions for peace education, because they appear to enhance knowledge about the conflict, and about “the other” particularly for young people who are direct parties to this divide.