This paper introduces good game design elements to consider for educational game. A suggested theory is applied on case study of educational history game development which was conducted by collaboration of game and education research experts. In the beginning of study, we seek for good game elements from the nature of play. We define and reorganize indigenous characteristic of play into two categories, Ludus and Paidia. Ludus is more oriented toward complex rule base game, and Paidia goes toward play attributes. We design and develop educational game based on suggested core design elements. At last, we observe how suggested good game design elements influences our educational game, addressing how to apply our design theory to the educational game development process.