Recent studies have shown that during the playing of violent online games, it is not increased aggression but rather alleviation in aggression that is critical in determining whether playing gaming has positive outcomes on the venting of aggression. Drawing from the aggression catharsis perspective and gaming research, we extend this line of investigation by exploring whether gaming results in a decrease in aggression, across a wide variety of games. Using data from a survey of 771 online game users in Korea, we examined the associations among Therapeutic Catharsis Seeking, Game Self-Efficacy, Big Five Personality Traits, Game genre (violent or nonviolent), Daily online gaming time, and Demographic variables. Results showed that therapeutic catharsis seeking and game self-efficacy decreased user aggression. Neuroticism negatively affected aggression while agreeableness enhanced the degree of aggression regardless of game genre. These findings have important implications for the use of gaming as a mood management tool.