But even if the technology works as advertised, there's no guarantee of success in a competitive games market.
How do these companies intend to succeed where others failed? One answer is by following Nintendo's example with Wii. MindLink and Bio Tetris failed in part because they didn't make the most of their novel interface. The games were really no different from what was already out there.
"With the Wii, Nintendo did something right in designing a suite of tailored games," Tan says. Wii games offer features that are not possible with a regular joystick, such as swinging the controller like a tennis racquet or brandishing it like a sword.
The mind-game companies intend to emulate this, though without abandoning the traditional controller altogether. Their games will still be largely controlled by hand, with biofeedback offering additional features. For example, Emotiv has adapted a game based on the Harry Potter books so that players can lift boulders and throw thunderbolts just by concentrating on making it happen.
Whatever form biofeedback games take, the world is ready for them, says Kiel Gilleade a computer games researcher at Lancaster University in the UK. The current market is less interested in finding new game genres than in looking for new hardware to enhance the gaming experience, he says.
Not everyone is convinced. Michael Zyda, director of the University of Southern California's GamePipe Laboratory in Marina del Rey, says biofeedback seems to work as an evaluation tool but he believes not enough research has been done to confirm its reliability in the real world. Hans Lee, head of technology at EmSense, agrees that more work is needed. One outstanding problem, he says, is that the hardware and software don't work for everyone. Reading emotional and cognitive states reliably is difficult because of each individual's variation in brain activity.
Even so, at least one company believes the technology is ready. Emotiv says its headsets will be on the shelves later this year, alongside a suite of biofeedback games developed by its partners. Biofeedback has been talked about in video gaming for years, but the real quest for hearts and minds begins here.
