From the 10,000 word post:
"The exact line between 'what the players ought to know' and 'what the players shouldn't know yet' is very, very fine indeed ... and playing that line is the best way to build momentum in a campaign. People have a built-in need to know."
I have written before about witholding information from the player. A little information is a tease; too much information is a cold shower.
As a DM you will find it difficult to restrain yourself, especially in your early experience. You will want to tell all about the interesting characters you've conceived, or the profound reason why the setting is the way it is, or how imaginative you've been in concocting the necessary solution. If you don't tell these things, you will bubble with excitement about the moment the party will find out ... and as a result, you will dowse the flame of your campaign. Your players will guess their danger or their next move by your inability to sit in your chair ... and when the next twist happens, it won't be a surprise. You might as well erect a red flag, then salute it.
A DM must be inscrutable. When the players chat among themselves and conjecture the exact thing you have planned around the next corner, you should not smile and blush and admit that "Yes, that's right!" Your face should be a closed curtain. No matter what a party does or says or asks, you must approach your game like a poker player. The more anxious a party becomes, the less intonation you should allow to creep into your voice. Once the party is excited, the less you say or give away, the better.
Why? Because it all ends when the party knows what's going on. Oh, they might still enjoy a last combat; they might enjoy distributing the treasure after a hard day's work ... but they'll have lost that itching feeling under their skin that demands they pull aside the curtain no matter what is on the other side. As a DM, you want them to believe it will be the worst thing imaginable - in their imagination, that is. There is nothing you can conjure with your imagination or words that will be as frightening as their imagination - so shut up and don't try. If you are inscrutable, they will project themselves onto the blank screen you provide - and if it turns out to be nothing, your player will be quite relieved.
And now and then, by sheer chance, you'll manage to come close enough to their imagination to get them really, really going. That's always a NICE session.
Dance and sing too much, though, and you'll ruin it.
Literature and film has long understood that there's a way to build up tension about something that hasn't happened yet that will keep the reader or the viewer on the edge of their chair. It is not as difficult as it sounds. Where you might be inclined to tell ALL about a thing, don't. An old trope is to describe everything about what a monster does without giving any information at all about what the monster IS. Another is to present a series of illogical events in which a rational explanation is impossible.
There's a game we used to play as teenagers. In effect, one person was the "game master" - he or she knew the answer to the riddle, and the others were forced to guess. The riddle was usually something that was nearly impossible to guess at first glance, as necessary information was deliberately left out. For example:
One day, a man walking down a street sees a sign in a restaurant window saying, "Fresh condor meat sandwiches served daily." The man says, "I haven't had a condor meat sandwich in years." He goes into the restaurant and gives his order to the server. The server brings out the sandwich, and the man bites into it. Then he puts the sandwich down, pulls out his pistol and kills himself.
Obviously, the question is why. The answer is conveniently on the internet, but before rushing to look it up, consider the rules of the game we played.
The Game Master was allowed to answer questions. The Game Master could only answer "yes" or "no." It was important that he or she not give away the answer with facial expressions or other clues - the inscrutability I described. The game is good practice for DMing.
Part of the game is that the players will ask again and again for the riddle to be repeated - and it's absolutely necessary that every word you use is the exact word you used previously. People will jump on you otherwise. So the game requires more than inscrutability ... it requires precision, as well.
We used to get a room of people very worked up as frustration kept them thinking and pondering and anxiously seeking the right question:
Was the sandwich made of condor meat? Yes. Was the condor meat fresh? Yes. Did the man actually taste the sandwich? Yes. Had the man actually eaten a condor meat sandwich before? No. Did he think he'd eaten a condor meat sandwich before? Yes. Did the man hate meat? No. Did the man always carry a pistol? Yes. Was it one he had bought? No. Was the pistol part of his job? Yes. Was he in the military? Yes. Had he been in a war? Yes. Had his supposed experience with condor meat been during the war? Yes.
And so on, until eventually you corner the game master with the solution. The man had once eaten human flesh, had believed it was condor meat, and upon tasting actual condor meat realized what he'd done years before, and could not live with the truth.
We had others. Some were painfully simple and could be solved in a few minutes. Some took ages and ages. I had one fellow on the hook for two years ... as this was before the internet, and he had no one he could ask. I would not give him the solution, and so from time to time he would ask me a few more questions and I'd give him a few more answers. He did, eventually, figure it out. I'm sure it was a weight off his mind.
D&D is like that for me. I will sit on the resolution for an adventure as long as it takes. In 2005 my online party was desert crawling when they came across three ogres hauling a bevy of girls to be sacrificed in a far off desert city. The party was new and weak, and three ogres was a tough battle. The ogres were in the employ of a wizard named Patroclus, who dwelt in the city of Khorezm, south of the Aral Sea ... and the party later met a few minor minions of Patroclus who tried to get the girls back. Not long after, the party returned one of the girls to her father the emir, who helped the party secure a periapt against scrying, whereupon Patroclus could not directly locate them.
In seven years of real time, the party has not heard from Patroclus. Not a word. But they occasionally acknowledge that Patroclus is out there, somewhere, waiting. They know that I know how he will re-enter the campaign, and under what circumstances ... and I do. The party worries about that. They should worry about that. It's a nice, long-term rumble beneath all the other unforeseen terrors they face. The less they know about the truth - from my perspective and from the perspective of the campaign - the better.
For some, this kind of long term puzzle would seem impossible. I argue that if you get good at not quite satisfying the party's curiousity, the party's curiousity will keep them coming back to your world ... potentially until your death.
Would be a shame, I suppose, if I were suddenly hit by a bus and the party never knew. But life is full of disappointments.