The use of video games as an educational tool initially causes a higher degree of motivation in students. However, the inclusion of educational activities throughout the game can cause this initial interest to be lost. A good way to maintain motivation is to use a good story that is used as guiding thread with which to contextualize the other video game elements (characters, scenarios, challenges, scores, etc.). A method is necessary for analyzing the effectiveness of the story in a video game. The authors propose an analysis method that includes user-centered techniques. This method has been applied to several cases of study. In this paper, they describe its application to the design of an educational video game in the field of mathematics and an adventure game for training the reading skills.