A risk associated with the use of games in training and education is that players "game the game," instead of focusing on their learning goals. The term "gamer mode" is proposed to describe this attitude. A player with a gamer-mode attitude strives to achieve goals that are optimal for winning the game, but suboptimal with respect to educational objectives. In this study of cadets playing an educational wargame to learn ground warfare tactics, the author examined occurrences of gamer mode. The results show that gamer mode on and off emerged in all analyzed sessions. Cadets' understanding of the wargame was different from what the instructors expected. This study discusses why it is important to avoid situations where the gamer mode emerges and also speculates on the sources that generate this attitude--the game itself, the educational setting, and the participants' previous experiences. (Contains 3 tables, 3 excerpts, and 2 figures.)