Given the increasing popularity of online game playing, the negative impacts of game addiction on both adolescents and adults attracted our attention. Previous studies based on the self-determination theory have examined the effects of the three basic psychological needs of autonomy, competence, and relatedness on problematic video game playing among Chinese young adults. Yet, as more evidence emerged pointing to the possible relation between need dissatisfaction and higher vulnerability for ill-being and psychopathology, the present study aimed to incorporate the impacts of both satisfaction and dissatisfaction for autonomy, competence, and relatedness in explaining Internet gaming disorder (IGD), a condition that may in turn impede eudaimonic well-being as indicated by flourishing. In a self-administered online survey with a valid sample of 1200 Chinese young adults aged 18–24 years (mean age = 19.48 years), the prevalence of probable IGD (for those who reported five or more symptoms in the Diagnostic and Statistical Manual of Mental Disorders (DSM-5) symptom list for IGD) was 7.5%. Our results showed that relatedness dissatisfaction positively predicted IGD symptoms after controlling for other need satisfaction and dissatisfaction. Also, flourishing was found to be negatively predicted by IGD. Finally, IGD was found to mediate the effect of relatedness dissatisfaction on flourishing. Our findings suggested a risk factor of relatedness dissatisfaction in predicting IGD, thereby significantly predicting flourishing.