Imagine playing through a level of the popular zombie shooter "Left 4 Dead" on a system that tracks your heart rate, eye movements, even how clammy your skin is getting, all to measure just how scared you are.
For 250 lucky — or extremely unlucky — test subjects, fear-based gaming was a reality, at least in an experimental program led by the game studio Valve. If the game could sense that a player was already frightened and frantic, it might ramp up the difficulty to make the gameplay even more frightening and frantic. The point? To make "Left 4 Dead" more fun, of course.
Valve's resident experimental psychologist, Mike Ambinder, said at a conference in San Francisco that the bio-sensitive tests "worked pretty well."
Game makers have struggled to escape the confines of the console for decades, and countless failed products like Nintendo's "Virtual Boy" system show an industry that's still trapped. In the last five years, motion gaming from the likes of Nintendo's Wii and Microsoft's Xbox Kinect has excited audiences, but it's not hard core: the best titles tend to be party games and fitness apps. Motion control may have brought players closer to their consoles, but a future generation of consoles, wearable and bioaware, will get closer to the players — and maybe even inside of them.
Right now, game controllers have rumble packs and "impulse" triggers to let you feel the game as you advance. So how do you make force feedback even more authentic? By sending electrical impulses straight into the muscles of your arms, of course.
"On smartphones, you usually have these little games," Pedro Lopes a Ph.D. student who worked on this project at Germany’s Hasso Plattner Institute, told NBC News. "But I wanted to see: Can we bring this extra degree of immersion? What people canonically have done is use motors. But those are big and heavy. Instead, we use your muscle as a motor."
For the study, Lopes and the rest of the team set participants up with a flying game to play on a smartphone. First, they used a motor-based system, then they used electrodes attached to their forearms. Overwhelmingly, the subjects opted for the "shock."
"They would say things like: 'I feel like this force is really coming from the game!'" Lopes said.
Augmented reality, virtual reality ... or just reality?
To researchers like Ambinder and Lopes, biofeedback is an essential ingredient for enhancing gameplay. But that's not to say it's the only ingredient. As the excitement for early stage prototypes like the virtual-reality headset Oculus Rift show, games are still evolving visually as well.
And while virtual reality is particularly alluring for all the "Matrix" imagery it conjures, it's not the only way to mess with reality.
Just take Dekko — a startup that recently raised $3.2 million in venture capital funding. It's releasing what founder and chief executive Matt Miesnieks likes to call a "real-world operating system."
"Everybody has some sort of imagination," Miesnieks told NBC News. "We would love to bring that to life. For instance, if you're a child, you might think, 'Wouldn't it be great if my Mickey Mouse doll could get up and start talking to me?'"
For its first in-house app, to be released later this year, Miesnieks said that Dekko is developing a tabletop boardgame that can be played entirely with computer-generated images.
"If you wanted to believably immerse the player in the real world, the object had to feel like the real world," Miesnieks said. He thinks that his company can finally give people "the moon" that "we were promised" — instead of "cardboard spaceships."
We're not in "The Matrix" ... yet
While total immersion is something game companies continually promise, is it something we even want? Football fans may relish the opportunity to stand in RGIII's shoes when playing "Madden NFL," but they probably don't want to feel his pain when a 350-pound lineman barrels into him.
Speaking at Kill Screen's recent gaming conference twofivesix, Palmer Luckey, the creator of the Oculus Rift headset, said that a big part of his job right now is "managing expectations" between the enthusiasts who expect "The Matrix" and the critics that see another Virtual Boy-style flop in the making.
Similarly, Lopes said that "we're obviously very far" from seeing anything like his electrodes pop up on Amazon, or even Kickstarter.
"The research we do is very vision-driven; these are not things that you'll have in your home next year," he said. "Maybe they will impact technology in 10 years."
While the software required for any AR system is certainly sophisticated, Miesnieks insisted that the real failure isn't that it simply doesn't exist. "The problem is that it's ugly and expensive," he said. But "Google seems to address that, which is really exciting."
Google Glass — the head-worn, video-capturing computer system — is certainly a beacon of hope for this kind of gaming gear, just as "life bands" like the Jawbone UP are for any developer hoping to make biofeedback sound like something other than pure geekiness.
But Evan Selinger, a professor of philosophy at the Rochester Institute of Technology, noted that there's something that may make these new kinds of gaming systems a reality sooner than expected: advertising.
A researcher may not care about collecting reams of data on a person's physiological or emotional state. But how enticing does that prospect sound to a company like Sony or Microsoft that is trying to ramp up e-commerce for its always-connected retail system?
"What marketers don't want you to think about is that now is it's all about marketing," Selinger said.
Yannick LeJacq is a contributing writer for NBC News who has also covered technology and games for Kill Screen, The Wall Street Journal and The Atlantic. You can follow him on Twitter at @YannickLeJacq and reach him by email at: email@example.com.