The inclusion of games in mathematics programmes is widely believed to foster the enjoyment of mathematics. The focus of this paper is on fluctuations in emotional climate during the playing of whole-class mathematics games. A multimethod approach drawing on the sociology of emotions was employed to explore changes in the classroom emotional climate that were associated with game playing. The event-oriented inquiry was conducted with two teachers and a class of 10- to 13-year-olds in a New Zealand classroom during mathematics sessions. Over a series of eight mathematics lessons, there were three noticeable fluctuations in emotional climate, all of which occurred during whole-class games. Our analysis of these three events identified a successful interaction with dramatic emotional energy associated with a positive emotional climate, a successful interaction with undramatic emotional energy associated with positive emotional climate, and an unsuccessful interaction associated with negative emotional climate with interactional repair. The third event also illustrated how the incomplete nature of a game's rules can provide an opportunity for a negative emotional climate to be associated with game playing. The taken-for-granted wisdom that whole-class mathematics games can enhance emotional aspects of a classroom learning environment is supported by some of our evidence.