In 1996, Scream pulled off the rare feat of achieving revolutionary status while offering nearly nothing new. Though many will point to Wes Craven’s most financially successful film as the pioneer of the self-aware horror flick—begetting not only three sequels but a host of imitators, all the way down to The Cabin in the Woods—Scream wasn’t even Craven’s first stab at going meta. Two years prior, Wes Craven’s New Nightmare blazed this metatextual trail that the director would embark upon, fittingly beginning his new Scream franchise (“Cause these days, you gotta have a sequel!”) on the heels of the re-imagined Freddy Krueger character that had cemented his name in the annals of horror.

Craven wastes no time conjuring up mental images of his most iconic creation. In Scream’s masterfully-shot opening sequence, the doomed Casey (Drew Barrymore) namedrops A Nightmare on Elm Street in the phone conversation with her soon-to-be killer, claiming that the first film was scary “but the rest of them sucked.” From the opening gun, Craven goes straight for self-reference, spicing it up with this in-joke about his distaste for many of the sequels. The references—both genre-wide and Craven-specific—only billow out further from there.

While horror movie tropes and pop cultural references flesh out the movie, Scream wouldn’t have become the highest-grossing slasher film of all time without a solid backbone. Craven’s crowning achievement is balancing the comedic elements with some truly grisly and frightening horror. With his starkly brutal opening scene, Craven proves that the slasher credentials of Scream will remain intact despite the accompanying mirth. A few references aside, there’s not much to laugh about in the opening scene, as Barrymore’s most memorable character since E.T.’s screaming Gertie is dispatched at the hands of a calculating killer. Much of the film may be tongue-in-cheek, but Casey’s liver is still going to end up in that mailbox.

The mastery of the opening scene cannot be overstated. As home-alone teen Casey makes stovetop popcorn in preparation for a flick on the couch, the urban legend of the call coming from inside the house (or in this case on the back patio) manifests itself. Casey plays along with the ominously-voiced random caller’s chat about scary movies (absentmindedly lifting a butcher knife out of the block as she does so), until flirtation turns to threats, much as Heather Langenkamp was tormented phone calls from Freddy in New Nightmare. Long tracking shots follow her throughout the spacious house as she locks doors and peers out windows. A trick question about Friday the 13th dooms her boyfriend, bound outside. Popcorn smoke clouds the house. After a short chase out into the yard, Casey runs directly towards the camera, where she is caught by her cloaked killer, who deftly plunges his knife into her chest. Unable to summon enough air to yell to her parents, who are returning home, Casey is dragged away. Her parents hear her last wheezing gasps through the landline phone, and they soon discover her hanging body outside, gutted like a fish.

The violence was so stark that Craven, after reading Kevin Williamson’s script, turned the movie down— twice. “I read the opening of Scream, and it was just brutal,” said Craven, who wanted to distance himself from slasher fare. “And I thought, ‘I can’t kill another poor girl.” What makes this opening sequence particularly shocking is that Scream offs its top-billed star in its first few minutes. The scene stands alone so well it could be an exemplary horror short; it’s truly a movie within a movie. After all, given that we eventually learn that the primary target is Sidney Prescott (Neve Campbell), Casey’s death is largely incidental. Craven maintains a sinister undercurrent, but the film turns far more comical as it goes along. We learn about sexless Sidney and her group of wisecracking friends, some of whom are victims and others, ultimately, the killers. That Skeet Ulrich, the poor man’s Johnny Depp, plays another bedroom window-climbing boyfriend (Billy) is another subtle callback to Nightmare.

Billy and Sidney define their relationship status by MPAA ratings (they progress to PG-13 when she flashes him), and every conversation that her pals Stu (Matthew Lillard), Randy (Jamie Kennedy) and Tatum (Rose McGowan) engage in invokes something cinematic. The film references are often direct (such as including attribution after a well-placed Psycho quote) and other times come off more jokey (“What is this, ‘I Spit on Your Garage’”). Craven turns up for a very brief cameo as a janitor in a Freddy Krueger sweater who is disturbed from his custodial duties by the school principal played by the Fonz. And at one point, a character cheekily conflates two masters of horror into a fictional “Wes Carpenter flick” reference. Scream dates itself with mentions of Ricki Lake and Tori Spelling , and as it presses on into its third act, the movie becomes almost overwhelming in its orgy of movie references—much like The Cabin in the Woods years later, a character outlines horror movie “rules” that proceed to play out before them.

Scream is so fixated on the movie-within-a-movie concept that, at one point in Gale Weathers’ (Courteney Cox) news van, we’re watching a movie whose characters are watching hidden camera video of Jamie Kennedy watching Jamie Lee Curtis in Halloween. Ultimately, Sidney defies her earlier critique of horror movie tropes by “running up the stairs when she should be running out the front door.” But after Stu and Billy reveal themselves as the killers—who then chide her for blaming scary movies (“movies don’t create psychos, movies make psychos more creative”)—she eventually dispatches them according to formula, literally smashing Stu with a Halloween-playing television and taking out Billy when he returns from the dead for “one last scare.”

Scream turns 20 this year, making it as old now as many of its most-referenced slasher films were then. Lazy satire consisting of pointing directly at tropes has become a subgenre unto itself these days. That Craven did it first doesn’t make Scream’s flaws any less apparent, though they can easily be overlooked when covered in the sheen of nostalgia. After all, Scream was a horror movie of a different time. When two real-life teenagers slaughtered their high school classmates at Columbine three years later, some talking heads blamed violent entertainment. Scream 2 would open with a brutal murder in a movie theater, something almost unheard of before Aurora, Colorado. When random mass shootings become so prevalent, the idea of revenge-minded, knife-wielding serial killers who follow set rules is almost comforting. After all, as Billy tells Sidney, “It’s a lot scarier when there’s no motive.”