Violence & Scariness. There's little actual combat in the game, but no shortage of disturbing and graphic imagery. The opening cinematic depicts the chase and murder of a young girl. Some spirits Marianne encounters are dismembered or feature other graphic wounds.
While not fear-inducing in the traditional sense, The Medium's oppressive atmosphere, surrealistic world-building, disturbing character design, and gloomy narrative all slowly lead towards an overwhelming sense of dread.