How to invoke fear or horror at your table top games!
"The Oldest and Strongest Emotion of mankind is Fear, and the oldest and strongest kind of fear is fear of the unknown." -H.P. Lovecraft
First, a few definitions: Horror, Fear, Dread, Terror, Disturbing, and Suspense
Before attempting any of the techniques make sure that you don't negatively impact any of your players. Don't play off of or use any of your players' real-world fears or phobias; don't translate those to your game.
Defining your flavor of fear/horror: Cosmic/Existential, Supernatural Fear, Personal Fear/Body Horror, and Psychological Horror