The game is short but I hear it is pretty damn creepy and Survival Horror is my favorite genre so I am sharing the news I just heard with you all.
It's called Slender, some details HERE: http://www.pcgamer.com/2012/07/05/slender-man-game-released-scare-the-he...
UPDATE: original links were removed SO I personally archived (WinRar) and uploaded the PC version for those interested:
Sorry cannot help with MAC version.
I will be grabbing it, the video is perfect. I love the look, its got tht creepy thing down. I wonder as he keeps looking up if something is going to drop down on you.. very cool, Wish i was home so i could take a look.