This paper describes and analyses a case of multidimensional collaboration of in the development of an educational game. The parties included Metropolia University of Applied Sciences from Finland, Tokushima University from Japan, and a lower secondary school in Helsinki. The development team involved students from three different departments of Metropolia. The two-year project produced two successive prototypes of the game, which contained two hundred questions about health and well-being including oral health. School pupils tested the game several times and commented on its features. They gave critical comments relating to its design and visual properties, even though they were positive about the idea of learning health facts in an entertaining way. Even though the coordination of such a project with many parties involved is challenging, the actual design of the real content and functionalities of a serious game pose more challenges. Effective advance preparation and research on educational game designs and aims will be needed in the following phases of the work.