Gabe Newell, Valve's strong man, confessed his admiration for the Wii Vitality Sensor - that odd peripheral for Wii that monitors your heart rate - during GDC.
"We think biometrics will be really important," he said. "We've seen a lot of work since the Wii shipped to explore how motion -- and with this next generation of controllers -- how vision systems are going to affect our games."
"Given that we have all these proxies inside of our games, that measure player state, we think that actually being able to measure small things like pupil dilation, heart rate -- those are the techniques that are going to give our games enormous impact in the future."