Valve has whipped the lid off its new obsession - and for those fearful of mad scientist-types, it's frightening stuff.
Having spent $50,000 on gaze-tracking technology to better understand where the studio's games testers are looking during play - and, subsequently, where needs the most development time - Valve is now turning its attention to biometrics.
That means hooking testers up to wires and passing a current through their skin - as well as tracking pulse rates, emotional reactions and other scary stuff.
Okay, so it's not exactly Human Centipede. But, as we say... mad scientists.
"So when you look at our games, more and more we have this representation of player state, where we think we know how you feel, essentially," Gabe Newell explained in the latest issue of PC Gamer.
"With biometrics, rather than guessing, we can actually use a variety of things like gaze tracking, skin galvanic response, pulse rate and so on. Through combining those pieces of information, we can get a much more accurate indication of player state, so that's something we're super interested in."
Newell revealed that Valve had conducted some "experiments" (mwah ha ha) in the space and seen some "easy wins" as well as some "surprising side-effects" - including possible benefits to consumer gameplay.
"If you're in a competitive situation and you see someone's heart rate go up, it's way more rewarding than we would have thought," he said. "And if you see somebody in a co-op game sweating, people tend to respond to that way more than we would have thought."
There are still barriers to Valve perfecting the rather-too-much-like-a-Half-Life-storyline idea for our liking.
But Newell is confident that with "medical technicians" on his side, Valve can find "non-clunky, non-stupid ways of getting that data "in the not-too-distant future."
Who fancies a QA job with Gabe then, readers?
You can read the full, fascinating interview with Valve on its history in the latest issue of PC Gamer UK - which is with subscribers now and in stores tomorrow.
Order the mag here and have it delivered to your door.