Even though game elements can increase motivation and engagement, they also might distract learners and thereby decrease performance and learning outcomes. In the current study, we investigated the effects of intrinsically integrated game elements on performance and learning outcomes. In a pre-post training study, 85 adult participants were randomly assigned either to the game-based or non-game-based training condition. Participants trained their fraction magnitude understanding with digital number line estimation tasks on five consecutive days (á 15-20 min). The learning outcomes were evaluated using a paper-based number line estimation task. While participants in both the game-based and non-game-based condition improved their fraction magnitude understanding from pretest to posttest, their improvement did not differ significantly. However, during the training, participants in the game-based condition responded more accurately but were slower than those in the non-game-based condition. The current results suggest that game elements might increase participants' cognitive engagement and change their priorities or strategies (i.e., accuracy over speed) during learning. Nevertheless, better training performance did not lead to superior learning outcomes.