In this paper the educational game Mythical Empires is proposed. Mythical Empires is a role-playing game (RPG) that aims at supporting Upper Secondary Education students getting prepared for the nationwide exams for admission in Tertiary Education in the fields of Economics and Informatics, in self-assessing their knowledge on the aforementioned fields. The design of the game is presented in the context of the CMX framework, along with the results of its evaluation by 88 prospective Informatics teachers through a survey based on the MEEGA+ model and the key criteria for game design proposed by Sanchez. Positive results on the perceived didactic utility and the anticipated player experience of the target group users were recorded, while improvements were highlighted. This pilot evaluation was deemed necessary for confirming and improving the design of the game prior its evaluation by the actual target group in order to draw solid conclusions on its didactical effectiveness and entertaining dynamics.