The general aggression model (GAM) has suggested that the interaction between person factors (e.g., personality variables) and situation factors (e.g., playing violent video games [VVGs]) can increase individuals’ aggressive behaviors through their cognition (e.g., hostile attributions), affect (e.g., negative affect), and/or arousal. The present study employed a modified competitive reaction time task to test the effects of shyness, violent (vs. nonviolent) gameplay, and shyness on individuals’ positive–negative affect, hostile attributions, and aggressive behaviors. In addition, the present study also employed structural equation modeling (SEM) to test the mediation (by cognition and affect) and moderation (by shyness). Results showed that playing a VVG increased aggressive behaviors, negative affect, and hostile attributions primarily among shy participants. In addition, the results of SEM also revealed that this moderating role was mediated by negative affect and hostile attributions. The present study supported GAM and showed that individuals’ aggressive behaviors are differentially susceptible to VVGs, depending on their level of shyness in a “for bad and for worse” manner.