SXSW may be the only film festival where the quintessential movies that play there aren’t just defining — they’re practically a genre. Here are some of the qualities of what has come to be seen as the classic SXSW film. It is violent. It is funny. It is aggressive. It involves murder and mayhem executed in flamboyantly nonchalant ways. It is on some level an action ride, though a ride with attitude. It’s smart about being debauched, and flippantly ironic about being smart. That’s what gives it the hip factor that’s the key to the SXSW secret sauce.

On that score, “Over Your Dead Body,” which premiered at SXSW tonight, has to be one of the SXSW-iest movies I’ve ever seen here. It’s a film that starts with a simple premise and sucks you right in. Jason Segel and Samara Weaving play Dan and Lisa, a married couple who have come to despise each other. He’s a director who made one movie and now directs pop-up commercials; she’s an actress on the off-side of Off Broadway. They’re doing a weekend at the cabin in upstate New York owned by Dan’s crusty father (Paul Guilfoyle). It’s just a getaway, but each of them has a hidden agenda. They’re both planning to kill each other.

That sounds catchy, and also gimmicky (it’s both), but the director, Jorma Taccona, who is one-third of The Lonely Island (he was the co-director of “Pop Star: Never Stop Never Stopping”), stages the first chapter of “Over Your Dead Body” as a knowing and relatable portrait of festering marital discord. Dan, no surprise, is an inept killer, a bit like the William H. Macy character in “Fargo.” Before he can chloroform Lisa, she winds up assaulting him with a taser; he wakes up bound to a chair, with his henchman — a low-grade flake named Henry (Jake Curran) — approaching her with a hammer. The unhappy couple wind up facing each other, descending into an argument where they come clean about all the rage they’ve been bottling up inside.

This part of the film is witty and almost believable. “Over Your Dead Body” is a remake of the 2021 Norwegian film “The Trip,” and the script, by Nick Kocher and Brian McElhaney, has plenty of lived-in detail about the triggers that can build up over time in a marriage. Like the fact that Dan is a culinary fetishist who has ordered special red pepper from Ohio, or that he secretly believes that Lisa is a lousy actor, or her resentment of the flameout of his creativity, or his savage mockery of her Australian accent. For a while, we’re more than happy to watch “Who’s Afraid of Virginia Woolf?” redone as a bumbling homicidal duet.

But that’s only the appetizer. At a certain point, a shotgun is fired into the ceiling, and down crash three hooligans who have been hiding in the attic — two escaped convicts, Pete (Timothy Olyphant) and Todd (Keith Jardine), and Allegra (Juliette Lewis), the corrections-officer-turned-killer’s-moll who has joined them. At that point, “Over Your Dead Body” becomes a very different film. It’s now a bloody cat-and-mouse game of the most extreme kind — a spectacle of sadistic survivalism gone mad, all staged with a logistically brutal joy. There’s a definite overtone of the Coen brothers in the way Jorma Taccone works. But it’s as if he’d taken off from the woodchipper scene of “Fargo” and said, “Let’s just kept that going.” The film keeps flashing back in time, overlapping the backstories of its characters, and that’s part of its playful fizz.

“Over Your Dead Body” isn’t a supernatural fantasy, but on some level it’s as demented as the early “Evil Dead” films. Hands are stabbed, feet are liquidated, fingers are severed, bodies are impaled (at one point an entire butcher block of kitchen knives has to be used to subdue Todd), an ear and a nose are bitten off, shotgun holes are blown into faces, and prison rape is treated as a parlor game. Fun! And yet…there’s a bizarrely spontaneous, randomly unfolding logic to everything that happens. The film features a slew of genuine performances, which power up the violent insanity into something at once sensational and dramatic.

It’s starling how much nuance Segel and Weaving are able to pack into this debauched blender of mayhem. Segel makes Dan a bitterly perceptive geek, out of his depth but eager to prove himself, while Weaving invests Lisa with a snappishness that only camouflages her pain. With the right vehicle, Samara Weaving could be a major star. Two of the villains are milked for laughs, but part of the strategy is that they’re played straight: Jardine’s Todd is an old-style muscleman hulk, reminiscent of Dave Bautista, but the character is serious about his obsessions (which include “Harry Potter”), and his bulk is used as a comic force. Lewis makes Allegra a horny scamp, and Olyphant’s Pete, the group ringleader, has a svelte savagery.

The violence gets more and more hyperbolic (by the time Dan’s father crashes into the picture in a sports car, we’ve entered a realm of madcap destruction), yet the whole thing remains tethered to the marriage of Dan and Lisa, who now, of course, team up in a couple-that-slays-together-stays-together way. Only the two never lose the ability to summon up their hate. “Over Your Dead Body” may on some level be a hyper-violent video game, but it’s like a video game staged by Hitchcock. It’s a lark, a gleeful bash of slaughter, a gonzo “Scenes from a Marriage,” and a slapstick-nightmare comedy of dismemberment, one that wears its heart on its sleeve, along with a few other body parts.