Imagine that you are dining with some people you have just met. You reach for the saltshaker, but suddenly one of the other guests, let’s call him Joe, looks at you sullenly, then snatches the salt away and puts it out of your reach.
(A) At the restaurant, this is rude. In the game just mentioned, this is expected and acceptable behavior. Apparently, games give us a license to engage in conflicts, to prevent others from achieving their goals.
(B) However, if you were meeting the same people to play a board game, it would be completely acceptable for the same Joe to prevent you from winning the game. In the restaurant as well as in the game, Joe is aware of your intention, and Joe prevents you from doing what you are trying to do.
(C) Later, when you are leaving the restaurant, Joe dashes ahead of you and blocks the exit door from the outside. Joe is being rude―when you understand what another person is trying to do, it is offensive, or at least confrontational, to prevent that person from doing it.