Morality emerges out of iterative voluntary games. What we regard as moral is the principle that most aptly governs the longest game.

It's an idea Peterson borrowed from Jean Piaget, a Swiss psychologist. Piaget focused on kids as ways to understand humanity at large. He believed that the act of voluntary play in kids is the precursor to ethical societies. The games are thus micro-cosmoses of society and as we grow up we are just extending the game into adulthood.