Choice and autonomy are central tenets of interest-driven learning. Yet, in most studies on interest in school, students' choice and autonomy have been confined within the boundaries of the curriculum and the subject matter in question. This limits our understanding of how schools can support interest-driven learning as well as students' interest development in educational settings more broadly. To address this gap, in this study, we have focused on student learning when they are allowed to follow their interests beyond the curriculum during school time. Building on relational and practice-based perspectives on interest, we conceptualized such extensions as productive deviations and centered on a particular case of two 6th-grade students -- Tamaz and Nuri -- who created two computer games during their time in the FUSE Studio, alternative STEAM learning infrastructure for schools. Our interactional analysis of Tamaz and Nuri's problem-solving during their game-making shows that their productive deviation formed a significant learning experience for them in terms of game design and working with computers. Overall, our study contributes to discussions on fostering and supporting students' interest-driven learning and interest development in school settings.