Ha ha ha!
I'm just drawing a loose analogy. The terms I choose might not be "modern" but I think they hold up and are sound. By natural law I mean a law that is in the nature set by the game. And I'm not saying that God is Illwinter but rather pointing out that we *could* look at it that way so to further illustrate the analogy with lex naturalis (in a scholastic sense).
Of course you can establish your own set of natural laws. But every player participating in the game have to agree upon that those laws are natural laws and thus cannot be broken. This have to be done in every game you play. Else the natural and unbreakable laws that apply are those that are set by the developers. Any other law (agreement) is artificial and can thus be broken (with the said consequences of course).