My CHI 2011 talk on how direct and indirect control enhance game interaction.
Nacke, L.E., Kalyn, M., Lough, C., Mandryk, R.L. 2011. Biofeedback Game Design: Using Direct and Indirect Physiological Control to Enhance Game Interaction. In Proceedings of the 2011 Annual Conference on Human Factors in Computing Systems (CHI 2011), Vancouver, BC, Canada. 103-112.