A great potential of educational computer games in learning process has prepared a good opportunity for teachers to apply "playful elements" in learning environments. As a result educational computer games are widely used as tools to entertain, instruct, motivate and develop skills. The effectiveness of a computer game in sense of help players to learn has been matter of game education industry for years. One of the best methods to assess game usability is game heuristics. Heuristics is an evaluation method that, has been developed and improved tremendously from general interface evaluation to specific evaluation such as computer game application. This study aimed to provide an easy to use, yet valid method to best evaluate usability of a game, it focuses on two techniques based on two types of evaluators; the expert evaluators and real users.