Please, remove this topic, It was a suggestion. I am not great to programming, but I don't know realy, what those games are about. I've heard this term. Please, move this topic.

I am aware of a few bio feedback projects and materials floating around, for example this recent article on gamasutra about available biofeedback SDK's that make use of web cam's and facial recognition to analyze a users current stress state, and how apparently easy they are to integrate into current frameworks. There are a few others of course, like neural feedback using EEG and ECG brainwave analysis, but the hardware for those isn't quite readily available yet, unless you count the OpenBCI project which ranges in price from 350$ to 1000$ depending on how pre-assembled you want it, though there working on trying to make it cheaper.

As this relates to games, basically it measures how stressed or relaxed you are, and changes the gameplay accordingly. In the examples given in the article, this means that the more stressed a player is, the more creepy the environment gets, and vice versa.