In this study, we evaluate the impact of a game-based supplemental fraction curriculum on student engagement, fraction knowledge, and STEM interest in inclusive elementary mathematics classrooms. Utilizing a robust experimental design, the research explores how a game-based interventions can augment traditional fraction instruction and promote STEM interest among students, including those with disabilities. The curriculum, grounded in Scheme Theory and Learning Trajectories, significantly improved students' fraction understanding and STEM interest. These findings highlight the potential of integrating game-based learning into mathematics education to address foundational STEM concepts and advocate for further research to explore scalability and broader applicability. The results of the study underscore the potential of innovative educational strategies to enhance learning outcomes and fostering interest in STEM careers among diverse student populations.