Designing an educational game can be a difficult task for individuals who do not have appropriate background towards game developments. Several game genres exist in the literature which can make beginners confused about which are the appropriate or required game elements and functionalities for a particular game genre. At the same time, many studies highlighted the effectiveness of mind-mapping techniques in enhancing learning and thinking task. Therefore, this study deploys the powerful graphical representation of Unified Modeling Language (UML) class diagram to present a mind-mapping guide for people who are developing educational role-playing games. A total of 113 students used the developed mind-mapping guide in a public Tunisian University, and the obtained results showed that the guide can: (1) significantly enhance beginner students’ level of knowledge regarding developing role-playing educational games; and, (2) promote the creative thinking when it comes to imagining educational role-playing game scenarios. Also, these results showed that students have a favorable attitude towards using the mind-mapping guide to learn and design their games.