Not only is game development an effective learning method for students (Hung et al. 2020; Bulut et al. 2009), but it can also be a good fit for student teachers (Schmidt 2024). Preliminary research addressing game design in general teacher training (Zapušek & Rugelj 2021) evidently demonstrates that the various activities and phases involved in game development (such as specification, design, rule development, implementation and evaluation) have a particularly positive impact on student teachers' motivation to learn and their capacity to convert subject-specific pedagogical knowledge into well-founded design decisions. According to Jonassen (2011), creating playful learning environments calls for a high level of problem-oriented identification of learning objectives and skills related to the subject matter. It also calls for the creation and assessment of learning strategies and solutions in conjunction with design considerations and knowledge about differentiation and special educational needs. As a result, it can offer future educators a meaningful application context that fosters creativity, helping them get ready for their future careers as learning environment and material designers. This presentation covers the framework, objectives, activities, and outcomes of a Masters-level action-research seminar for aspiring English language teachers. The main question to be addressed is how this seminar with a focus on material development can contribute to the development of relevant competencies of EFL teachers for designing, implementing, and evaluating competency-based, motivational English instruction. This will be done by describing and reflecting on the processes of game-development, the products, and the research conducted by the student teachers.