In the past decade, virtual worlds have demonstrated the potential to be the next generation of interface for entertainment, interaction, content, and e-commerce. As a major type of virtual worlds, online games become a huge business and engage millions of players around the world. However, e-commerce researchers have so far paid insufficient attention to why players enjoy using virtual game worlds. To address this insufficiency, the current study develops and empirically tests a theoretical model of determinants of online gaming enjoyment. Specifically, this study suggests that key elements of online games are the primary factors associated with the enjoyment of playing an online game. The current study also investigates the impact of enjoyment on gaming behavior while we control for other known critical variables of attitude and subjective norms. The proposed research hypotheses are tested by using questionnaire responses of 253 online game players. Overall, the results indicate that online game story, graphics, length, and control are highly related to enjoyment, and that enjoyment has a significant impact on behavioral intention even with the presence of control variables.