Developing new gamified educational resources or educational games takes time, and it is natural to want to ensure the success of their integration in the classroom. For this reason, it is important to look at the role of the teacher before and during the implementation. However, research on gamification and game-based learning has been focused on students, and very little has been said about teachers (Kenny & McDaniel, 2011). This study contrasts two teachers’ experiences of the implementation of a gamified app with regard to their participation in the design process. Interviews with teachers and video data from the classroom have been analysed to find out how the teachers experienced the implementation and in what ways their involvement in the project is reflected in their respective experiences and in the accounts of their experiences. The analysis reveals that the two teachers have had very different experiences of the implementation. Where the first teacher developed familiarity with and ownership over the application, the second teacher felt lost and stopped using it. Involving teachers through co-design or using flexible instructional designs has advantages, but other factors should be considered when implementing new resources (e.g., class context, teachers’ previous experience, teacher training). This study opens up new questions on the teacher’s role in the integration of games and gamified applications in the classroom but also raises the issue of their potential participation in the design of new resources.