Honestly, I didn't think it would be out this soon.
Parsec Productions (The creator of Slender: The Eight Pages,) has revealed what seems to be a final (?) version of his game. Links to the website (And the video), will be posted below.
Since I'll bet most people here have played Slender: The Eight Pages, I'll spare you a description of the game.
Here's the main site:
http://slenderarrival.com/The creators of Marble hornets have even joined in in development.
(
http://blueislestudios.com/marble-hornets-creators-join-development-of-the-arrival/)
It is planned for release in early 2013, which, maybe for you, has already come.
EDIT: Forgot to mention...
Jeff the killer may be in it?**The other figure shown in the teaser could possibly be a "Proxy"; Someone who does Slender Man's bidding through his influence.See more information here:
http://theslenderman.wikia.com/wiki/Slender:_The_ArrivalRumors about Development:- Upon the release of the official trailer, rumors were raised that the Rake will be included in the game.
- A possible third game in the Slender series is an idea, creating a Slender trilogy. Mark Hadley, creator of The Eight Pages and The Arrival, said that "there very well could be another sequel. [The game staff] have had a lot of ideas for names of this possible third game, like Slender: The Last Page and such."
- In December Hadley confirmed that a third game is now underway. Also he stated that he has plans to release another 3 more games after that, making 6 games in total.