Question: In a horror themed campaign with a Lovecraftian feeling, a big part of the game is a constant feeling of threat, but without any visual stimuli other than glimpses, or sounds vaguely heard of things seething in darkness, and with investigation a big part of the game, contrary to fighting.

Having read *Heroes of Horror*, I am searching for ideas on how to actually motivate players to assume the role of investigator rather than executioner, and how to instil the horror of the unknown, of something that threatens but is not substantial, that cannot be seen or heard, but is there, and has malevolent intent.

I am thinking of D&D 3.5 as a system, but I am interested in answers that cover any system (Call of Cthulhu is unfortunately out of the question), more as role-playing and storytelling techniques rather than mechanical ones.

Answer: 
It's a horrifying feeling for PCs when they get to what they think is the end of the trail, the cause of all the distress and pain and suffering, the root of all evil, and then there's a small reveal that tells them they are just beginning to scratch the surface of something much more profound.

The demented, inbred freak held captive in a basement inside the old mansion can drive PCs insane, control them with its mind, and send its minions against them in waves. The triumph of finally overcoming this foul villain becomes something else entirely when its last words are, "Finally, I am released. Finally I am free of it. If only the rest were so fortunate!" The PCs now know this adventure, which taxed them mightily, is nothing but the prelude to a much bigger battle against a tremendously powerful enemy with resources beyond imagining.

After bashing their heads against the minions of this unseen force, the PCs will start to realize the only way they have even a sliver of hope of surviving is to stop attacking its limbs, its proxies, and start trying to find its heart and its head. Once they're in that mode, it's easier to start introducing more bits of paranoia, because they'll be trying to fit the pieces together. Pretty soon everything will start to look to them like it's part of a bigger pattern.
One of the big keys of maintaining pressure is use of pacing and establishing a good baseline of tension and then amp up and ease off at the right points.

These videos are about video game storytelling, but can easily be applied to Table Top:

[Extra Credits: Pacing](http://penny-arcade.com/patv/episode/episode-07-pacing)

[Extra Credits: Where did the survival horror go?](http://penny-arcade.com/patv/episode/where-did-survival-horror-go)