Mobile games have emerged as the most innovative entertainment technology, adding new revenue streams, taking advantage of the potential of wireless applications and service offerings. Mobile games, as well as PC games, Video games and online games, offer a unique value for users in providing an exciting digital experience in virtual worlds. The overall trend for mobile games is towards bigger, more colorful, more involving and exciting contents, which might build upon the developing capabilities of mobile phones and networks, in order to bring new styles, concepts and experiences of game play to the users. In this paper, we investigate the factors influencing the usage and acceptance of the mobile games, based on the extended version of the Technology Acceptance Model (TAM). Based on data collected from online survey, we show that perceived usefulness, ease of use are the major determinants for mobile game users to play games. Four factors, including ease of use, self-expressiveness, visibility, and innovativeness are empirically shown to determine the level of perceived usefulness; additionally, innovativeness and facilitating conditions are shown to directly affect ease of use. Based upon the statistical results, some useful guidelines for game development and market penetration strategies are also provided.