The Proteus effect of exergames has been widely regarded as a factor that influences human performance and learning. Within the context of security and defense exergames, identification with a digital alter-ego affects students' task performance as well as their emotional states. In the present study, we examined the influence of the perceived masculinity of male avatars on players who were engaged in gamified military exercises (based on competition and command) in a three-dimensional environment. Analysis of data that were obtained from 51 male learners using semi categorized interviews revealed that, during the game, participants with more masculine avatars were more self-confident, engaged with the task, and obtained higher scores than their counterparts with less masculine avatars. Moreover, when they adopted an avatar that they perceived to be more masculine, they reported improved mood, self-confidence, and decisiveness after the completion of the game.