In recent years, digital games have assumed an important place in the lives of children and adolescents. Effective content design is crucial to the success of digital game-based learning. Therefore, the tool for assessing the effectiveness of game design is accordingly very important for parents and teachers, so that they may encourage or discourage students to play. The purpose of this study is to develop an assessment tool to examine the educational values of digital games. In the first phase of this research, the research team developed the indices for assessing the educational values of digital games. An expert panel consisting of game scholars and professional game designers was established to construct the indices for evaluating digital games in three focus group discussions. Seventy-four game evaluation indices were sorted into seven categories: mentality change, emotional fulfilment, knowledge enhancement, thinking skill development, interpersonal skill development, spatial ability development and bodily coordination. In the second phase of the research, the game designers were asked to assess certain games by using the 74 indices. Meanwhile, the game scholars were also asked to evaluate the same pool of games by the same indices. The assessments by both the scholars and designers were then compared and the similarities were found. This research provided a preliminary framework for future game designers, parents and teachers in assessing educational values of digital games.