This study examines the influence of game genre choice on the development of computational thinking (CT) in school-based video game design activities. While previous research highlights the engagement and motivation benefits of game design, limited quantitative evidence exists regarding its impact on programming skills. In this paper, we investigate the relationship between game mechanics or content and CT concepts development. A quasi-experimental study was conducted with 146 students from Finland and France (2022–2024). Students selected from ten game models spanning diverse genres, and their choices were analyzed based on initial programming proficiency and gender. Platform and jumping games emerged as the most popular, while quizzes and visual novels were preferred by female students. Results indicate that game genre choice correlates with both student interest and programming difficulty. Post-test results show overall CT skill improvement, with variation depending on the game type created. Platform games and visual novels yielded the highest learning gains, whereas quiz games showed the lowest. The presence of gameplay elements involving specific CT concepts, such as loops and conditionals, was directly linked to improved mastery of these concepts. Based on these findings, a progression of game types has been proposed, beginning with simpler games before advancing to more complex designs. These results contribute to educational game design research, supporting the hypothesis that game types and mechanics influence programming knowledge acquisition. Future studies should explore broader contextual factors and their impact on CT development through game design activities.