His hand jerked back in instinctive repulsion. Sword shaking in his grasp, horror and revulsion and fear almost choking him, he backed away and down the glass steps with painful care, glaring in awful fascination at the grisly thing that slumbered on the copper throne. It did not move.
—Robert E. Howard, “The Devil in Iron”
Over at The Delver’s Dungeon, there’s an interesting thread about whether you can have a frightening dungeon crawl.
I’m of the opinion that while it’s very difficult to scare players who don’t want to be scared, it’s very easy to scare players who do want to be scared, as they’ll do all the heavy lifting for you. It’s a matter of personal investment; the more immersed a player is in the game, the more likely it is that they’ll react emotionally to what’s going on—whether or not you intend for that to happen!
If your players are fully engaged and you’re aiming for a bit o’ fear, there are a couple of factors you’ll want to bring in:
1) Threat: If the players actually value their characters’ lives and put themselves in their characters’ shoes, then they’ll be at least a bit scared of anything that they recognize as a serious threat to the PCs. Note that this is a matter of perception rather than fact! In my game, the players often charge into fights with powerful opponents without too much worry, but they’re chary of ghouls because several encounters with ghouls have resulted in near-TPKs.
2) Mystery: Sometimes unknown danger is more threatening than the known, because it could be anything. For at least a dozen sessions, the thing in my dungeon that most unnerved my players wasn’t a monster, but a stairway. It was an enormous thing that wound deep into the earth, its lights growing dimmer as they went down until it disappeared into darkness. They didn’t know how far down it went or what lived at its base. This allowed them to invent their own fears.
As a player, what have you found scary in a D&D session? As a DM, what have you done to scare your players during play?