Abstract: This research aims to explore the impact of cooperative or competitive gaming modes on players’ emotion and behaviors. We conducted a with-in subject study with 30 participants. Participants were asked to play a fighting game with a male research confederate in two different gameplay modes. We examined (1) self-reported preference, (2) changes in the gamers’ emotional states, (3) facial expression data captured by emotion recognition software, and (4) video recordings of the gaming sessions. The statistical results showed no significant differences. However, we were able to identify unique behavioral patterns shown in the competitive gameplay mode.