Same problem as dead space, its not scary. Monsters in horror is so overdone that they are just no longer scary. Take amnesia for instance, the game is only scary when you don't see the monsters, the more you see the monster the more desensitized you become. Amnesia is scary because it builds on psychological horror and plays off fears created in the players mind not what is on screen, the same is true with slender man. To make a walmart horror movie it would have to take a fargo kind of plot with a middle of nowhere walmart.