This study explores the factors influencing students' online game-based learning (OGBL) performance. At present, motivating students to engage in learning actively represents a significant challenge faced by teachers and other stakeholders. Additionally, the findings of a variety of OGBL studies have been inconsistent or contradictory, particularly regarding virtual rewards. This study integrates self-determination theory and flow theory as a theoretical basis for analyzing data collected from 105 undergraduate students using a quasi-experimental design and the partial least square structural equation modeling (PLS-SEM) approach. The results reveal that students' intrinsic motivation positively influences their enjoyment and focused attention. Autonomous motivation positively influences their learning performance. Furthermore, intrinsic motivation and focused attention are critical mediators in the proposed research model. The findings of this study contribute to the application of self-determination theory and flow theory in the OGBL context and provide suggestions for teachers and stakeholders with regard to promoting students' learning.