The most effective intervention model for childhood obesity is known as family-based behavioral group treatments. There are also studies that investigate the effects of educational games for children to gain healthy eating and physical exercise habits. The aim of this study was to compare the efficacy of a family-based group treatment with an educational game (Kaledo) intervention in childhood obesity. Kaledo is a board game that was designed to improve nutritional knowledge and healthy life style habits. It is played with nutrition and activity cards that players can select from, and a total score is calculated in the end of the game according to energy intake and expenditure. Obese children between 9 and 12 ages were involved in this study. Participants randomly divided into behavioral and game intervention groups. Clinical evaluation was performed in the first and second counseling in both groups. Marmara University Family Medicine Department Obese Children and Adolescents Interview Form, Physical Activity Evaluation Form, and Three-day Food Record Form were used for this purpose. Strengths and Difficulties Questionnaire-Parent Report Version and Children's Depression Inventory were used for the assessment of psychiatric symptoms. After the clinical evaluation, an education session about healthy eating and physical activity was attended by both groups. After that, for the behavioral groups, parents and children were assigned to different groups, while for the game intervention group, parents were assigned to behavioral sessions and children were assigned to game (Kaledo) sessions. A total of six sessions with 1-h duration and 2-week interval were performed in both groups. Height and weight were measured in each session and analysis was performed on the data of the children who participated in all of the sessions. Although a total of 108 children were clinically evaluated, 52 children and their parents, 26 in the behavioral group and 26 in the game intervention group, participated in two or more sessions. Twenty-four participants, 12 in behavioral and 12 in the game intervention group, finished the study by participating in all of the six sessions. Thus, dropout rate was 74%. BMI and BMI z-scores decreased in both groups compared with the initial measures and these changes were statistically significant. For the behavioral group, these changes were - 1.01 (25.44 to 24.43, p = 0.03) and - 0.17 (2.07 to 1.90, p = 0.000) and for the game group, - 0.74 (26.98 to 26.24, p = 0.007) and - 0.09 (2.07 to 1.98, p = 0.003). There were no significant differences between behavioral and game intervention groups in point of BMI and BMI z-scores (p = 0.130 and p = 0.706).