Social platform services have transformed the lifestyles of individuals and the entire information and communication technology (ICT) ecosystem. The growth of the social networking market and the evolution of social networking sites (SNSs) have promoted a new wave of social network applications such as social network games (SNGs). SNGs are online or mobile games played through social networking sites or applications in which people interact with friends. SNGs are a new service that merges the playfulness of the game contents and the mutual relationships between people, emphasizing sociability between players. This study investigates the primary effects of usefulness, ease of use, playfulness, social image, and maintaining interpersonal interconnectivity, factors that affect user intention to use SNGs and positive word-of-mouth (WOM). An extended SNG user acceptance model is proposed that applies the Theory of Reasoned Action (TRA), Motivation Theory, Technology Acceptance Model (TAM), and socio-technical perspectives. The impacts of playability and sociability are investigated in this study. Also, the relationship between sociability and user intentions in SNGs is verified through the results of this study.