At first I imagined how hi-res cameras could track head movement & dilating irises of eyes but that would take up too much CPU space for current hardware to clean tacking images & calculate in real-time.
Next I realized current Playstation specs would work. Then I tried to generalize the idea for more than just PlayStation hardware.
This resulted in wrapping neon tape around the sides of glasses to monitor. The length of color along the glasses can indicate which direction the face is turning.
The troublesome part of this is it not only relies on the size of the TV but the distance away from the camera & TV.
With a large TV, most eyesights can only see blobs of color outside of focused area.
So in order to optimized this idea, there needs to be a measured distance away from the TV so the person’s head has to move around to see.