I was married for 17 years to a woman diagnosed with NPD, so this thread is of interest to me for sure. I have not read past this post yet, but this does raise a salient point...
The part about if a narcissist can be "fooled", tied to the rules being what ever the narcissist wants them to be at the time...
In order for a person to be "fooled" or to be "wrong" in anything or any situation, they have to actually be aware that they were fooled or wrong.
Without that self realization, self awareness, then they are never fooled and never wrong. A narcissistic personality will always rewrite the rules, reframe the situation so that they were not fooled or wrong.
Regardless of how it is presented, those who are looking to beat a narcissist at their own game, wanting some sort of revenge, wanting closure, are asking for the impossible, because what they are really seeking is for the narcissist to have some sort of "ah ha" moment, to give some sort of acknowledgement, and with a true narcissist, they lack the portion of personality that would allow for that.
With a narcissist, the only way to win is to simply not play.