I don't know that the Slender Rising series is the best iteration of the Slenderman game or not, but I quite like it. I think it's very atmospheric, I like the controls and the graphics, and the details of what you can do worked better for me than the original Slender: The Eight Pages did on the PC, at least. More options, more atmosphere, and better playability.
I'm not sure how many readers may be familiar with the Slenderman games and the Slender Rising series in particular. To start, you pick a landscape (from four). The "classic" Slenderman landscape is a forest, but there's some great ghost towns, abandoned houses, and others as well. You pick an ambiance--a really foggy daytime, night, night-vision, and a thunderstorm in the dark (my favorite.) You might also have the opportunity to pick a type of light (flashlight with unlimited battery; flashlight with a risk of battery loss, or lantern, etc.) Then you wander around the landscape looking for seven pages with cryptic and sinister clues written on them in blood. Once you find all seven, you unlock the escape, and--if you can find it--you can escape the level. The whole time, Slenderman, a teleporting ghost or some other such other supernatural entity, tries to hunt you.
This is where a comparison--or perhaps contrast--to RPGs as they are usually played, came to my mind. In D&D, for instance, you could have a scenario where you wander around a haunted forest looking for MacGuffins, while pursued by a supernatural creature or creatures. This could even be a successful D&D scenario, with a real touch-and-go feel to it, and the obvious nods to the horror genre would be evident. But... you'd be fighting the monsters. It would be more thrilling rather than terrifying.
In Slender Rising, you can't fight Slenderman. You don't even have any weapons at all (well in number 2, you might get a shotgun, which you can fire once to chase him off for a moment. But it's not likely that you will find it, really, anyway.) You're only recourse when Slenderman appears is to run away as quick as you can in the opposite direction. If you go into a blind alley and find yourself blocked in, you're screwed. If you can't run away fast enough, you're screwed. The game ends, and you die.
Actually, the case of the shotgun in Slender Rising 2 is kind of interesting. You can get a weapon (that would be deadly in most cases) but it's only effect is to chase Slenderman off for a moment. You can't actually defeat Slenderman at all. The only thing you can hope to accomplish is to escape.
While not all horror stories end this way (in Dracula, for instance, Van Helsing, Jonathan Harker and Lucy's three suitors manage to chase the Undead down in the mountains of Transylvannia and kill him. Sure, Lucy and Quincy pay with their lives, and Mina and Jonathan are scarred as well, but that's not really a bad ending, all things considered. But in many, there is no real victory, and at best only escape. In The Ring, for instance, in the end [SPOILER ALERTS] the main characters escape but leaving the menace lurking in the dark for others to find still. In fact, if anything, the menace is somewhat enhanced by the method that the main actors used to escape. In the movie from a year or two ago, Woman in Black, the protagonist and his son are killed by the titular ghost. In The Grudge, similarly, the protagonist makes--maybe--a temporary escape at best, but is left at the end still haunted.
In Slender Rising you can, if you're lucky, escape the ghost (I'll be honest; I've never done so. It's too hard. And I don't play all that often to get better at it either.) But you can't defeat it.
Is that an acceptable outcome for RPGs, I wonder? I think many players would say so, especially if they buy into the concept of playing a horror game in the first place. But I think many players would feel frustrated by this paradigm, too--the notion that you can only escape, not defeat, the Bad Guys™ or whatever. As always, knowing your "audience" is key to a successful game experience. But I'm curious if anyone has adopted this paradigm before; a very overtly horror paradigm, in your gaming? In my experience, most overtly horror games don't even do so frequently, but sometimes it works out that way. I've had good experience using this for a Dread game, for instance. I know it can work with the right players, and it can work very well and be a very powerful experience, even. But trying to pull it off when the players show up with a typical D&D paradigm in mind is likely to be frustrating for everyone.
I originally included a trailer for Slender Rising, but decided that a slightly longer gameplay video would be better instead. You don't need to watch the entire thing to see that even in the daylight, the atmosphere is just incredibly creepy and ominous. The first attempt the player makes is in the Lost Souls mode, where instead of finding seven signs posted on the walls, you need to find seven ghosts and set them free.