The main use of biofeedback is for stress. That is what it has really been used for over the past 3 decades. It's a non invasive way to get treatment for stress and stress related disorders.
In most cases biofeedback uses a game interface to interact with a patient. The game interface is to keep their concentration a bit better though the treatment session. There are not too many game variations and most involve some sort of object moving back and forth on the screen.
