I've said it more often than not: to make a movie work, in its simplest composition, one of two things must happen. The good and great movies have both these things happen, but at least one needs to be there if you want an audience to pay attention, invest interest, and believe in the characters and what's happening to them.
The first thing is forward motion. Whether through dialog, character development, actions, or effective editing, without visual or story movement from start to finish, the movie won't work. Leaving an audience sitting around hoping for something, anything, to happen is not the way you want them to feel. And what happens must evolve and not just happen willy-nilly.
The second thing is to make a decision up front and stay committed to it. Is the story funny or serious, quirky or cheeky, or a carefully blended mix, and why is it that way? If a director can't make up his or her mind in how they show us this, the audience won't be able to make up its mind, either. Remember Tim Burton's Dark Shadows remake mess? He couldn't figure it out and neither could we.
Perhaps more significantly, a director needs to know what to explain or not explain, and if a situation of "no explanation" is desired for artistic or dramatic reasons, how can you achieve that through what's shown or not shown, heard or not heard, to keep an audience satisfied with their investment in your story. Unsolved mysteries can be annoying or tantalizing: if you do the first thing really well, no one may notice, or care much, that you didn't tie a pretty bow to wrap up the second thing neatly. Horror movies, especially, suffer from franchise-itis endings, where a tidy and satisfying story is butchered by an ending that doesn't, sacrificed for a potential sequel.
Director Akiz tricks us into thinking he's covered both of these things, but he sort of does, sort of doesn't, so Der Nachtmahr pulls us in just enough, leaves us wondering and wanting more explanation, just enough, and provides just enough to fill in the gaps as we choose. I'm not sure if he intentionally did this or a lucky accident occurred here, but this is the kind of movie you won't see too often from Hollywood. It demands active viewing not passive, and its characters aren't at all endearing or clever or the kind of people you want to hang around with. Or maybe I just don't want to hang around with them. They are vacuous (okay, maybe not the philosophically-minded student, but he's in the minority), living vacuous lives filled with pretensions.
There are the usual foreign film idiosyncrasies like time wasted listening to students (really just that one nerd in the group), who are hanging out, discussing deep philosophy on a level similar to how many Einsteins can fit in God's head and fractals (but so serious you wish it were more humorously intended, like Animal House's stoner view of the solar system under your fingernail.) Of course, the American film idiosyncrasy found in horror movies involves students, who are hanging out, discussing male and female anatomy and party protocols. So there.).
Akis does go bananas with his rave scenes. They are jarring, overly loud, and filmed with an arrogance and a diffusing color as his camera follows the hedonistic friends through their partying and drug excesses. In contrast to his endless malaise saturating every scene, these disorienting raves hint he's making a point about his characters and their priorities. So which nightmare you choose to see is up to you. Tina sees the creepy one, which meanders around without saying anything and is always hungry, forming a symbiotic relationship so what happens to it happens to her. Perhaps its aimlessness is hers. When it bites into a razor blade cutting its tongue, her tongue is cut. Her parents see that as a cue she's reverting to old habits. Her counselor tells her to talk to it. But it doesn't speak. Her friends start retreating.
A Donnie Darko moment of time rewind violence jars the storyline toward confusion and possibly a Tangent Universe. Or not. Hard to say, given there's a backstory to Tina (Carolyn Denzkow), alluded to through her visits to a counselor and an ever-present concern, despair, defeat, and anxiety felt from her parents. Then the police are called, a creature is seen (similar to the one in Fuselli's 1781 painting), and off we go, seeing through Tina's mind what she believes is happening, or seeing the reality as perceived by those around her.
The movie shifts into an Eraserhead kind of visual weirdness, but takes too long getting there and doesn't dare enough, and takes us for a car ride at the end to wonder where we're going or where we've been. Too much vibe when more jibe with the two must-happen things I mentioned above, would have made the movie work harder for us so we didn't have to.