For years, people have wondered why 2009’s smash zom-com “Zombieland” never had a sequel. Ruben Fleischer’s feature directorial debut put him on the map and firmly established the postmodern zombie craze as a pop phenomenon that shows no signs of stopping. It cemented Emma Stone and Jesse Eisenberg as legitimate stars and even gave Woody Harrelson a midcareer boost. Since then, Eisenberg and Harrelson have been nominated for Oscars, and Stone has won one. Fleischer and writers Rhett Reese and Paul Wernick have found box office success shepherding the Marvel Comics superheroes “Venom” and “Deadpool.”

So the really weird thing about this sequel, which reunites the original stars and filmmakers, is that it imagines a world where the past decade never happened. It feels like a movie that’s been sealed in a vault for 10 years, lost to time, waiting for cinematic archaeologists to liberate the dusty old relic from its tomb. A character wears a Juicy Couture tracksuit and no one comments on it, for crying out loud. Sure, she’s been trapped alone in a mall, but the film ignores the opportunity to mine the time lapse for real laughs. And the mustily misogynistic humor on display wouldn’t have even played in 2009 anyway.

“Zombieland: Double Tap”(a double entendre referring to both the mechanism by which one likes an Instagram photo, and Eisenberg’s character’s approach to confirming zombie kills) imagines a world where “The Social Network” never happened, positioning Eisenberg as the nerd who gets the girl despite being unforgivably self-involved. Even Stone is in full snarky cool girl “Superbad” mode, side bangs and all. Watching this film is like experiencing an alternate universe where the stars never grew up (despite Abigail Breslin’s best efforts) and neither did the humor. But the world changed. This slapdash cash-grab sequel is not nostalgic, but in a word, taxing.

We find the fearsome foursome of Tallahassee (Harrelson), Columbus (Eisenberg), Wichita (Stone) and Little Rock (Breslin) playing house in the White House when we catch up with them. Columbus quickly gets us up to speed, reminding us of his endless zombie survival rules, while Fleischer reminds us of his self-reflective on-screen text tic. Although Columbus wants to settle down with his woman, Wichita, watching the odd family rattle messily around the Oval Office isn’t all that interesting, so Wichita and Little Rock take off. When Wichita returns with the news that Little Rock absconded to Graceland with a pacifist hippie, Berkeley (Avan Jogia), the group gives chase. Tagging along is Columbus’ new love interest, airhead mallrat Madison (Zoey Deutch), whom Columbus triangulates between himself and Wichita to spark her jealousy.

Deutch and Jogia give their all to the tired stereotypes with which they’re saddled, while the rest of the crew fuss and whine narcissistically about their love lives. In this apocalyptic wasteland, they dehumanize anyone but themselves. The plot only perks up when new elements are introduced, like a pair of doppelgängers, Albuquerque (Luke Wilson) and Flagstaff (Thomas Middleditch), who appear all too briefly, and a fun moment with Rosario Dawson driving a monster truck. But it feels like any new ideas were jettisoned for the same old shtick. “Zombieland” may have helped to give birth to the zomb-aissance, but “Double Tap” just might be the kill shot.