Writer/director Gaspar Noé has chosen to reverse his chronology nonetheless, with a narrative structure ripped off from Memento .
(Think Memento, only better.)
Working, like "Memento," with 10 ten minute scenes shown backwards (Noe even has fun with his audience by beginning his film with its end credits scrolling backwards) and like Hitchcock's "Rope," in uninterrupted takes cut together against dark backgrounds, Noe proposes that rather than advancing, humankind has regressed to a bestial state.
But like in "Memento", this gimmick serves a purpose.
Like "Memento" (2001), the other recent film told backwards, "Irreversible" features characters behaving tragically because they are unable to know, as we are, what is going to happen next.
Told backward, á la Memento, his story of the story of a vicious sexual assault (of Monica Bellucci's character) begins with her boyfriend's revenge.