IdleJon
I don’t remember thinking that it was complicated. I do remember thinking that it might have been written by a pretentious 6th former. 😀
Assuming you mean the ‘sci-fi’ interpretation (and depending which cut of the film), i’d be surprised if you got it without reading an explanation because a lot isn’t explained well (or at all). For the full ‘sci-fi’ explanation you need to read the book which was on the website to understand the manipulated dead, that he can perform telekinesis, why he had to flood the school etc.
There are a lot of other interpretations though which are easier to follow (it’s his descent into schizophrenia from his own perspective, it’s him reimagining his life in his final second before death etc etc).
edit: i’m not endorsing it as a good film, i wouldn’t say investing the time to understand it is worth it