Dream of the Bad Moon is a first person free horror game, inspired by the viral phenomenon
While Dream of the Bad Moon lacks the lo-fi 'Blair Witch' feel of Slender, it makes up for this with an uneasy eeriness. The puzzles required to get each tear also make this a more complex experience. The monster chasing you is similar to Slender, although she seems easier to keep track of as you flee from her!
What Dream of the Blood Moon also does well is graphics. They may not match an AAA title, but they look good, and there are some lovely effects along the way.
It's not revolutionary, but Dream of the Blood Moon has clearly been made with care, and not simply churned out to latch onto the Slender phenomenon.