I've started making a map of the Black City (surface ruins) and sketching out some encounters. As I've said before, my stated goal for the Black City was to see if a megadungeon could be built with themes from weird horror. (It takes all types, right?)
Its got me thinking about horror and D&D, and how to achieve it. I've DM'd a lot of Cthulhu in my time, ran The Transylvania Chronicles during the 90's in my V:tM phase, and I've always thought D&D was strongest when it had a strong element of horror.
There's an old post by Mr Raggi where he declares that much of the pulp fantasy is basically horror, and that D&D is a horror game; I won't rehash his position (go read the original - D&D is a horror game). No, instead, I'll be laying out different ways to achieve moments of horror in your own D&D game.
First off - about horror. Horror is not sustainable; it's fun in doses. Just because I'm discussing a megadungeon, don't think I have designs to place one horrible thing after another in there; who'd want to play it? Even the typical Call of Cthulhu scenario has a certain pace; a horrible thing is discovered, the group gathers facts and performs their investigations, the horror deepens as they piece disparate clues together, and then there is usually some kind of confrontation to resolve the story. To appreciate those peak moments of horror, there needs to be the chance for the tension to dissipate, even a bit of humor, much like cleansing the palate in between courses of a meal.
Without further ado, here are some tried and true approaches to achieving gaming horror, tailored for D&D. (I wanted to log these so I can refer back later - inspirational reading to warm the cockles of my heart, and all that).
Chuck game balance out the window, and don't be afraid to put dangerous monsters into the dungeon. Deadly monsters. I believe in giving the group fair warning, and a chance to flee or otherwise avoid instant death, but fear of beating eaten is the easiest way to achieve momentary dread.
D&D is its strongest as an exploration game; not too many monsters, plenty of empty space, and a growing sense of weirdness and dread. My players are about halfway through Death Frost Doom right now, and the pace of exploration in that module does an excellent job of playing against player's expectations and building a sense of dread.
Fear of the unknown - the simplest approach here is using some non-standard monsters and keep the players guessing.
A similar technique is the hit-and-run. An evasive monster that gets in, does its business, and gets out. They're never sure when or where will be the next attack.
Steal a page straight out of HPL, and craft the revelation of the adventure to hinge upon some awful truth that gets revealed much too late. "The reason we can't find the descendants of the family in the dungeons below their ancestral castle, is because they devolved into the horrible rat monsters that keep ambushing us from the dark…"
Shocks and Scares
It's cheap, but the occasional table-trick can spike the sense of terror (and then give everyone a good laugh). Slam a book, suddenly raise your voice, do something startling at the game table, right when everything is quietest.
A similar technique is changing up the physical staging - trying some dimmer lights in the game room, candles, that kind of stuff.
This is a staple in Cthulhu gaming, though I wonder how many D&Ders would think it too outré. At some point, the group has to do something horrible to avoid something even worse from happening. One of my favorite Cthulhu scenarios, Beyond the Mountains of Madness, features a gruesome choice to avert a greater evil. So does The Black Drop (for Trail of Cthulhu), which we played last summer. Crosses over into head games a little, so know your group.
The Ick Factor
Gross out stuff is a nice shock from time to time. There's an awesome (gruesome) sequence I remember from Masks of Nyarlathotep, where an investigator drops into a pool of leeches. Blech. Leeches rate super high on my personal creepy scale, too many times encountering them at summer camps. But you get the idea - a momentary gross out, harmless or not, will rattle some players.
The Awful Mistake
This is another staple of Cthulhu gaming that ports over fairly well; give the players an opportunity to pull the innocent looking lever that unleashes horror on everyone else. It may not seem fair, but it's a lot of fun for the DM. Plus you get to spend all that time picking up the pieces of your campaign.
A good technique to build dread is to have something horrible happen to the next guy, as a bit of foreshadowing. This is why NPC's are born; to die horribly and serve as a cautionary tale for the characters. What did I read recently? "Henchmen taste like chicken". A more advanced technique is to do a cut-scene or other 'storytelling technique' so the group gets a view of what happened to someone previously, off screen; then when they start to encounter similar circumstances, they get locked right into that sense of impending doom. "Don’t you remember how Hopkins died? It started when he heard the same kind of scratching at the door. It has found us".
Loss of Control
Situations that force the player to lose control of their character are unnerving. I wouldn't overuse them, but they can heighten terror. Charm effects, mind control, soul-crushing fear that paralyzes the character in place while the monster slowly makes its way over to feed on the now helpless character - yeah, that's dreadful. I loved those slake moths in Perdido Street Station.
This is the essence of survival horror, right? Too many monsters, not enough bullets. It works in D&D too, trapping the group with limited resources and making them fight their way out before they lose light, food, and water. Chutes and slides, anyone?
You see this in the horror gaming, but it may be a bit too much for D&Ders. Something terrible happens that undermines the character's bodily integrity; for instance, getting knocked out by sleep gas, and when the character wakes up, something's been surgically altered; they have a gorilla hand where they used to have a human hand. Or everyone has been infected with alien embryos, or parasites, and they only have a certain amount of time to get a cure. Another example is the disease that's slowly turning the infected into plague zombies.
The enemy is among us. Has anyone tried using a doppleganger in a castle or village, where there are plenty of NPC's to die vicariously? An old '90's D&D adventure, Night of the Vampire, did a good job of having the monster mingle amongst the revelers at a ball, picking off victims throughout the evening.
Fate Worse than Death
Present the players with something that is worse than dying. The acid monster that destroys the remains so thoroughly, there is no Raise Dead possible. (Or the soul-sucker that does the same). This is a good one to team up with Vicarious Horror, so the players can see it happen to someone else first, heightening the terror.
I'll add to the list as I come across more - it's certainly not exhaustive. Let me know in the comments if you've used a different way of achieving moments of horror in your own D&D games!