The aim of this paper is to analyse the acceptance of online games, based on the unified theory of acceptance and use of technology 2 (UTAUT 2). The data analysed correspond to a sample of online players through mobile devices in Spain. A structural equation approach based on Partial Least Squares was used to assess the acceptance model. The result of the analysis indicates that UTAUT 2 explains 71% of the use of online games in mobile devices. The main conclusion of the study highlights the importance of habit in the use of online games. Specifically, the intention to play online is explained, in order of importance, by the variables habit, hedonic motivation and social identity. In addition, the use of an online game is determined by habit and intention to play. We proposed a simplified UTAUT2 model adapted to the online game scope.