This paper reports a study conducted to formally evaluate a social problem-solving skills game during the start of the development to ensure that the desired game attributes were successfully embodied in the final game. Two methods, heuristic evaluation and participatory design, were adopted to assess whether the features of the game pose playability issues to the prospective young users and to translate the participants' contributions into game design directions. The participants playtested and evaluated the game based on the Pedagogical Playability Heuristics, which are different from existing heuristics developed for commercial games, as priority was placed on instructional design principles and the concept of playability. Using storyboarding, they built low-fidelity prototypes of the game. Suitable children's design and feedback on the games attributes that would bring about stimulation, connecting instructions to goals, appropriate challenge and influencing goal achievement were integrated into the game design. As a consequence of the study, steps were taken to improve the game as an interactive system to achieve the instructional goals and at the same time foster enjoyment among the users. (Contains 2 tables and 6 figures.)