Background: Goal setting has been established in the literature as a critical component of self-regulated learning and for effective problem-solving. Yet, surprisingly little attention has been focused on goal-directed behaviour in digital game-based learning environments (GBLEs) despite their expanding use in educational contexts. Objectives: The current study examined the impact of goal assignment in a GBLE aligned with curricular objectives and played in a classroom context. Methods: Eighth-grade students (N = 59) in the experiment were randomly assigned to either a mastery goal condition or a performance goal condition before playing "Crystal Island--Outbreak". Goal orientation was measured before gameplay, monitoring judgements assessed during gameplay, and enjoyment was measured after game play. Results and Conclusions: Two important results emerged that contribute to the existing literature on goals and GBLEs. First, assignment to the mastery goal condition resulted in significantly higher enjoyment ratings and monitoring judgements but not game performance while considering the influence of pre-existing goal-orientation. Second, self-reported mastery goal orientation and videogame play frequency predicted enjoyment in the game. Implications: The results suggest that enjoyment can be facilitated by orienting students to adopt mastery goals and that developers should consider integrating mastery-based instructions in their GBLEs. Moreover, instructional goals can influence students regardless of incoming goal orientations.