Background: In the 1970s and 1980s, there was considerable discussion about the potential of student-designed games to help students develop a more refined and deeper understanding of games. Unfortunately, despite these sophisticated conversations, there has been limited empirical research on the effectiveness of student-designed games, particularly as they relate to learning. Aims: To examine students' learning during their participation in a unit of student-designed games. Method: Two classes of boys (aged 14-16) at a school in England attended one 40-minute lesson a week for 7 weeks. Each class was divided into three teams and participated in four phases of development: a 2-week library-based planning and wiki construction phase; a 1-week outdoor modification and wiki update phase; 3 weeks of trials of the games with a wiki refinement phase; and a 1-week game and wiki finalization phase. In these lessons the pupils designed an invasion game to be played in a subsequent Sport Education unit. Data were gathered from teacher reflections, interviews, observations and analysis of the game design process. Data analysis occurred through the immediate and ongoing efforts of the teacher-researcher to meet the "on the spot" learning needs of his students; the systematic collection, organisation and analysis of the gathered data; and the peer debriefing, which occurred throughout the collection and writing processes. Results: Three themes were constructed from analysis of all data sources. These were labelled "learning how games work (game appreciation)", "learning what makes a good game (and in consequence, how to design a good game)," and "what was easy, and what was difficult in the games-design process." These themes are discussed within the context of what the students did and did not learn, what they found easy or confusing, and how their understanding and appreciation of games improved. Conclusions: The student-designed games provided a forum that allowed students to develop a more sophisticated understanding of game structures and game play, but designing games was not easy. However, the findings of this study support the idea that when students design games they discover the impact of the many elements that make up a game. (Contains 3 tables.)