A game is above all a set of rules dictated by its designer. The most direct link one can have with the designer’s ideas is through the written rules—if they are properly written of course. They are the “pith and marrow” of the game.
“The rules of a game are absolutely binding and allow no doubt… As soon as the rules are transgressed the whole play-world collapses”. Unlike Huizinga, I’d claim that in many cases when the rules are transgressed, new play worlds emerge.
When reading a new rule book, I’m engaged, excited, and retaining everything hungrily until I hit the first exception. At that point, the rules have picked a fight with my memory and are fighting back against me understanding and internalizing the rules.