Nevermind [official site] is a game which uses biofeedback devices like a heart rate monitor to create a responsive horror experience as the game tracks your level of fear. I've written about it before but now it's popped up on Steam Early Access.
The Flying Mollusk team (for thus the development studio is named) are opening the game up as a work-in-progress to get feedback from players with the supported heart rate sensors.
"We want to get input from players (who have these devices) on how responsive each sensor feels so that we can both refine our integration and effectively support as many devices as possible!"
At £18.99 it's not a particularly cheap feedback experience, but reading through the Early Access info it sounds like money from Early Access sales is going to go towards expanding the game from the three levels its current funding will support to five.
Nevermind started as a Master's thesis project for Flying Mollusk CEO Erin Reynolds - the idea was to marry a horror aesthetic with a game which offers something positive to the player. That positive offering in Nevermind is that it aims to reward you for learning to manage your own fear and stress responses. How it does that is when the biofeedback sensor registers an increase in your fear and anxiety levels the game gets harder. Being able to control those responses and to calm yourself makes the game more forgiving.
Alas, as fascinating as I find the idea, I do not own any of the biofeedback devices which you can use with the game (yet) so I can't try out the build to see how it works. If any of you have given it a go let me know how you got on, otherwise I'll see if I can borrow a heartrate monitor from someone.