What you don't do that? When GMing pen-and-paper RPGs, I was told it was easier to create a mystery, let the players create an elaborate explanation for how and why, then just nod and congratulate them on their cleverness in figuring it out. (No, I'm not kidding.) In fact, I did do something like this once. That game I had concocted an elaborate evil conspiracy, and the players were slowly unraveling it (as they should). However, one of them realized the implications of some plot elements I had missed and so deduced that the conspiracy was even more evil and far-ranged than I had intended. Naturally, he and the other players immediately thought this was the original plan of the cabal all along. Since it was so much better than what I had planned, I changed course on the spot.