Slender: The Eight Pages, formerly known as Slender is a free experimental game developed by Parsec Productions. It was released as a beta in June 2012 for Windows and Mac OS X.
Found it boring and slow paced with low detail in the environment. I have played mods better than this. The gameplay is directionless and plotless. Also a bit irritating as I was taken to the titlescreen with no explanation as to why after walking around in the woods very slowly for about 15 minutes.