Slender is a free game by Parsec Productions in which you play as a woman armed with a mighty flashlight, who must for some reason collect pages, numbering 8...in a park...during the night. To make matters more traumatic for this woman, there might possibly be the Slenderman lurking about...
For those who have never seen Mr.Slenderman, he is a friendly being that likes to hug things with strechable (sometimes multiple) arms, is tall and skinny, and likes to wears a suit. For some reason the woman, and those that play the game seem terrified of him...
Few horror games thrust you so directly into the heart of fear. All of Slender’s elements – the lack of a map, the threat of instant death, the slight element of unpredictability of the page locations – all contribute to a pervasive sense of hopeless vulnerability as you frantically flee an unknowable predator who may or may not be directly behind you.
The game can be downloaded for free here! Here's a trailer, just in case you aren't convinced to get it yet:
Edit: Updated links since the old ones no longer work, and added link to new homepage for the game!
Link to game (Windows/etc.)
Link to Slender Website
Link to Parsec productions (goes to another, rather less scary game. Unless you have pancakeophobia... which isn't a word I just made up...)