[jonchurch_]

The knowledge that I can end a given session by closing my eyes feels very good and natural. It also gives it a bit of a "game" type of experience.

But I'd encourage you to think about the experience you're trying to create, in terms of how to handle the sensitivity of blinking for ending a session. With a single blink being the end, then it becomes very easy to accidentally end a session (either via a bug in false positives, or of course just doing the human thing of blinking).

If you want to maximize time spent staring into a human's eyes without looking away, then the session could end after say 1-2 seconds of eyes being closed, or looking off screen. Then the choice to leave is a bit more intentional, and so sessions can last longer for folks who really want to see how long they can stare at a stranger without tapping out.