In efforts to make a film about local folklore, Heather, Mike and Josh (Heather Donahue, Michael C. Williams and Joshua Leonard) get lost in the woods in this 1999 pseudo-documentary they should have called Paranormal Maptivity.

Presented as the tapes recovered from the missing filmmakers’ cameras, The Blair Witch Project is not the first “found footage” feature but it is unequivocally the best and should probably have been the last. What quickly became a gimmick is chillingly believable here, and not just because of the novelty at the time. While the ingenious marketing tricks (including listing the actors as missing or deceased) have worn off, the film’s scare tactics still leave you shaking like a handheld camera.

Even knowing the story is fake, the movie feels real because the actors are genuinely terrified. And that’s ultimately what we’re buying into, not mid-Atlantic myths and legends. A big reason the vast majority of horror movies fail is because the brain knows when it’s being tricked. The best genre films tap into something primal and real, and it doesn’t get much more real than sending three rookie actors into the woods and fucking with them to create a true guerrilla chiller.

Though it draws on the faux-vérité style of Night of the Living Dead, The Texas Chain Saw Massacre and Cannibal Holocaust, Blair Witch is unique in being purely improvised, and shot entirely by the actors themselves. It breaks the convention of showing the characters’ point of view by making us see only what their cameras see, creating horrific moments when they freak out about something out of shot.

Yet the picture is also ingeniously edited by directors Daniel Myrick and Eduardo Sánchez, crafting eight days of raw footage into a compelling 80-minute narrative that builds more or less like a traditional horror flick. But the technique of making the story in the edit blazes a trail for 21st century media, blurring the line between reality and fiction with a level of credibility that might as well be witchcraft.

This is horror without a safety net, a rugged exploration of our relationship to the genre and what happens when we strip away the artifice. Deceptively simple and deviously innovative, the $750,000 project is one of the greatest horror movies ever, even if a glut of found footage imitators has burdened it with a Blairite legacy.