Slenderman: scary, yes? Possibly the last thing I’d expect while playing something other than a Slenderman game. Oh, but he’s out there, waiting, in Runner2 according to this video by Epsilonic.
See here, the official teaser for Faceless, a game previously known as Slender: Source. It’s got a complicated lineage: inspired by another game, which was in turn inspired by an internet meme.