10 Great Sci-Fi Movies Under 90 Minutes

With its headwrecking narrative, unexplained paradoxes, endless timelines, and its tech-heavy dialogue, it's sensible not to try to understand Primer. This psychological indie was made to be experienced, not comprehended.

The story centres around two engineers, Aaron and Abe, who decide to test a time machine they accidentally created. (If you're wondering how you can accidentally invent time-travel, that's the least confusing part.)

Because the budget was under $10,000, Primer has none of the flashy effects you'd expect from a blockbuster. Despite being made for peanuts Shane Carruth's directorial debut is more thought-provoking than a dozen $200 million sci-fi epics put together. Its minimalism benefits the film since the lack of CGI and sprawling set-pieces don't distract viewers when they're trying to figure out what the hell is going on.

Primer is so dense, it's easy to assume the plot is pure gibberish. Only by watching it three or four times (or more), will you start to scratch the surface.

If you've already seen Primer, you should give it another go. Whatever you thought of it upon your last viewing, you're guaranteed to see this mind-bending thriller in a whole new light the next time around.