Background:
Game-based learning is an effective learning method, whose performance depends on the quality of the educational game. Due to versatile game environments with complex backgrounds, evaluations are not easy to implement.

Materials and methods:
This study designs a Flow dimension questionnaire in which some domain experts are asked to re-examine the attributes of the Flow dimension by using the Delphi method. The extracted attributes of Flow dimension are then employed to build the proposed model for evaluating a given educational game. For practical implementation, this study developed an Evaluating Mobile-Learning Game System (EMGS), based on the proposed model. In the case study, several experts were requested to use the developed system for evaluating three different types of educational games.

Results:
The results show that the developed system is faster and more convenient than the traditional evaluation method, and the developed system could effectively recommend the best qualified educational game for educators in different situations.

Conclusions:
The case study and system satisfaction questionnaire verified that the evaluation process provided by this system is fast and convenient, and that it can give an accurate recommendation to assist educators in selecting the most appropriate games for learning.