I'm going to suggest my favorite movie of all time, a little understood masterpiece by filmmaker Tristan Newcomb. I'm talking about Only Interstellar Pinball Lives Forever. There is no other film in the entire universe even remotely similar to OIPLF, Newcomb made the entire feature length film himself, all credits go to him except for the guy who made the music and two extras who appear in one brief scene and don't say anything. The movie is a conversation between the adult Newcomb and a childhood vision of himself represented by a puppet he frequently uses Dobo Disty (who has actually been in a couple short films Newcomb has submitted to the Escapist's own film festival). The child puppet, unwilling to accept the mediocre life which has become the main character's, and terrified of dying, delves into a confused discussion of death itself, opting to use the metaphor of a pinball machine.
Newcomb has described his work as "the dark side of puppetry," and it's more than evident here. The sheer terror of death manifested by the film's ramblings makes it probably the most scary film I have ever seen (as in, after you watch it, you're probably going to have to ask yourself some serious questions). It won't be everyone's cup of tea, but if you like a film that'll really make you think, I don't think you can afford to pass it up.