This article describes the development and assessment of a coding scheme for finding both usability and fun problems through observations of young children playing computer games during user tests. The proposed coding scheme is based on an existing list of breakdown indication types of the detailed video analysis method (DEVAN). This method was developed to detect usability problems in task-based products for adults. However, the new coding scheme for children's computer games takes into account that in games, fun, in addition to usability, is an important factor and that children behave differently from adults. Therefore, the proposed coding scheme uses 8 of the 14 original breakdown indications and has 7 new indications. The article first discusses the development of the new coding scheme. Subsequently, the article describes the reliability assessment of the coding scheme. The any-two agreement measure of 38.5% shows that thresholds for when certain user behavior is worth coding will be different for different evaluators. However, the any-two agreement of .92 for a fixed list of observation points shows that the distinction between the available codes is clear to most evaluators. Finally, a pilot study shows that training can increase any-two agreement considerably by decreasing the number of unique observations, in comparison with the number of agreed upon observations.