Sometimes during a gaming session people will reminisce about games played in the past, and we will sit and listen to somebody share an anecdote about a game that was played previously even if we have already heard the story, even if everybody at the table was present at that particular event. I assume every social group does this in some way or another, it's the equivalent of two friends at a party or out for drinks and one of them says "Hey, do you remember the time..."
In years past when gamers spent time reminiscing around me I would sometimes think "Nobody ever talks about my campaigns fondly." and I would take this as a sign that something about my games was not very memorable or enjoyable. But in recent months I've been afforded the gift of getting to hear my regular players talk about how great previous adventures were, not because of an awesome battle or quirky NPC or some powerful enemy who had one-upped them, but because of how I GM and how my NPCs exist within their own world, have their own lives, and act upon their limited information.
Let me set the stage for you:
The players had been tracking a criminal organization from planet to planet and every time leaders of this group tried to interact with the PCs they got killed. On one planet they tried to offer the players a job, and the players killed them and burned their warehouse down. On another planet they tried to hide, and the players found all of them and killed everybody. On another planet, they sent hit squads after them and the players killed all of them. Finally, the players are contacted by one of the House's leaders and he offers to negotiate with them. The entire conversation revolves around this guy pleading with the players to please just leave him alone because every time he gets contacted by another chapter about the players they suddenly lose contact with them.
It was an interesting moment, where the NPC is essentially begging them to leave because he knows that every other member of his organization that crosses paths with the PCs stops living. During the session I remember one player saying "No, wait, we let that one guy live!" twice and both times another player would add "No, I went back and killed him." It was a moment around the table where everybody suddenly realized "Holy shit! They must think we're some elite assassination squad!" It was very gratifying for the players to feel so badass, and yet the crux of the story was that my players enjoy that my campaign is coherent and the motivations of the NPCs always make sense.
Something so simple, but I'm proud that I've reached this point as a GM.