It was originally marketed as a "Horror", picked up from a festival, purchased for 1,000,000 pounds. The marketing was fantastic, true Guerilla marketing. My favorite tactic was the paying buskers around central London to play out their theme tune on loop, with the movies poster behind them.
For the movie itself, after bombing, it was then re-marketed as a thriller and eventually resurfaced to gain what is now an outstanding "Cult Status". It's the simple grasp of existence, do we really make a difference? Or are we just dust in the wind?
Do i believe the movie is like no other? for it's marketing, yes. But existence is questioned in most films, perhaps not to that degree, but i assume that the film being categorized as "Not like any other" has a lot to do with the marketing, and a limited take on existence.