Have you ever wondered what an Asylum Films version of Slenderman would look like? Why? Why did you will this into reality by thinking about it? Ugh, whatever.
There have been a couple of Slenderman movies over the past couple of years, and pretty much all of them are bad. I can't speak to the quality of the HBO documentary, but I don't necessarily count that one anyway.
Although Slenderman is a beloved part of internet folklore, he's a copyrighted character. Somebody owns him and has exclusive rights to use the character. That means if you don't have his permission to make a Slenderman movie, you won't make a Slenderman movie. Unless of course, you avoid ever using the character's actual name or likeness, play with him just enough to make him recognizable but never actually show him, and just call him a "Slender Being" instead of his actual name.
That's how this movie came to be. A zero-budget, zero-talent, zero- originality schlockfest that rips off the notability and likeness of Slenderman but stops just short of anything that can get them sued, this is a Z-movie bootleg.
Even if you can forgive the movie for being a tasteless ripoff (I can forgive "Due Date" for being a blatant ripoff of "Planes, Trains and Automobiles" because it's entertaining) you'll find yourself being slowly tortured by the bad editing, endless filler, scenes that never pay off, scenes that have nothing to do with the rest of the movie, scenes of people yammering about nothing, and massive flaws that go directly against the most basic rules of filmmaking. This movie is a disaster, like bad poetry in motion.
If I held this movie to normal standards, I'd have to call it one of the worst films ever made. However, I can't even count this as a real film. Generally, "indie" films are excluded from my list of the very worst (because there's so, so many bad ones) unless they can hit that sweet spot where they're coherent enough to count as a real movie, but bad enough to be garbage.
This is not coherent enough to be a "real" film. This movie is a mess. This is a bootleg Slenderman film, and it isn't even a good bootleg. Avoid it like you'd avoid the real Slenderman.
