In this study, we attempt to identify motives pivotal in choices made regarding online and offline game genres and assess whether they are meaningful predictors of Internet addiction. A separate goal was to determine how an assessment of Internet-related cognitions compares to criteria-based research instruments on Internet addiction, and demonstrate its clinical usefulness. We are using data from a cross-sectional study of the entire adolescent student population aged 12-18 of the island of Kos. Results indicate that specific game genres and motives for choosing a game are important predictors of Internet addiction, even after accounting for sociodemographic and Internet-use-related variables. Gender differences are not statistically important when we account for genre choices and motives for choosing them. Boys' thought content tends to revolve more around their Internet use compared to girls. Several patterns of motives to play specific genres were identified with the help of a canonical correlation analysis, demonstrating the fact that the simple observation of overt behavior is not enough to deduce the meaning of these actions for the individual. Using multiple measures of online addiction, examining genre preferences and underlying motives for choosing a game can be helpful in reaching a better understanding of the individual game player.