This is a weird movie. Weird is a high benchmark to achieve, as most artists know that different is a virtue, thus many outsider mediums have developed their own genre, like art-house and meta movies, that all carry their own set of expectations and tropes. So it's not often that a film simply defies categorization, which is the case with Der Bunker.
It may be a black comedy as it certainly has a sense of humour, but it really only makes you laugh uncomfortably over how screwed up the entire situation is. There's no goofy gags or obvious punchlines, just a general sense of amusing absurdity.
It may be a horror as the circumstances are quite grim, yet there's not a monster to be seen and very little could be construed as scary. There's a pitch black hopelessness, but the intent is not to be frightening in any way.
It may be an art film, though I feel the aforementioned sense of humour diminishes any sense of pretentiousness. It often operates on a surrealistic dream logic, but the plot does have a solid backbone, so it's linear and easy to follow even though it's totally insane.
It could be a family drama, as that's basically what drives the story, but I hope it's clear from my earlier synopsis why a feel good coming of age film this isn't.
All in all, I found it thoroughly enjoyable. My one criticism is that the voice they used for the gash in the woman's leg was a little cheesy, but even that sentence further illustrates how nuts this movie is.
It's a crying shame how overlooked Der Bunker seems to be. I understand it won't be for everyone, which explains the often lukewarm reviews, and if you're looking for a simple blockbuster, get out now. I'll even admit that I wasn't overly enticed by the cover/trailer, and have been pushing this down the "watch later" list for a while now. But if you have a taste for the strange and have been contemplating giving it a shot, throw it on now! Trust me, you won't regret it.