I bought this game only yesterday and beat it within an hour I believe. All in all, I do not regret buying it. Is it short? Yes. Is it badly optimized? Oh yeah. Is it scary? Nope...Seriously, if you call this game scary, then you probably need to play an actual horror game like Outlast. But for some reason, I just can't justify giving this game less then four stars. Trust me, it deserves two, maybe three stars at max. But my personal experience with the game was so fun that I just need to give it four. If you are new to horror games and just want a bit of short fun that's also an entry level horror game, I'd say go for it. If you are a die hard Slender Man fan and need your dose of Slendy, I'd say buy it (Or just go watch the entirety of Marble Hornets.) Now I'm neither new to horror games, nor am I really a die hard Slender Man fan but if you just feel the need to play this game like I did, then know that it's just a fun little badly optimized (That can be mainly fixed by turning the shadows off) short trip into a Slender Man nightmare.
Same as matthew1974, just does not detect the base game. But I will still give it five stars because I know this DLC will be awesome once GOG gets it working properly.
While this game is very good. I felt it was lacking In the whole "This game ties up all loose ends" thing. I just felt like it didn't really tell me anything I didn't already know. But gameplay wise, its still outlast. So if you enjoyed outlast, then your probably going to pick this up regardless.