Techniques for controlling a casino game machine include detecting, via one or more muscle activity sensors worn by a player of a wagering game played on the casino game machine, voluntary muscle activity of the player while playing the wagering game on the casino game machine. The detected voluntary muscle activity of the player may be analyzed to infer a state of the player indicative of the player's level of interest while playing the wagering game. The inferred state of the player may be mapped to one or more game adjustments appropriate for increasing a likelihood that the player in the inferred state will continue to play the wagering game or another wagering game. The game adjustments may be applied by changing one or more operating parameters of the casino game machine controlling one or more aspects of the wagering game while the player is playing the wagering game.