What can we expect from film studios deeply committed to marketing pre-existing brands beyond creative death due to excessive nostalgia? An occasional pleasant surprise, it turns out.

Given its mindless source material — a dusty, 1980s, giant monster arcade game — “Rampage” ought to be monotonous and boring. But instead of just trying to cash in on our memories, it has the spirit of a project put together by people who enjoyed playing the game. Like “The Lego Movie” or “Kong: Skull Island,” it embraces the cartoony kitsch of the core concept and has fun with it. I was hooked early on and found it entertaining right to the end.

Dwayne Johnson plays primatologist Davis Okoye, and the movie’s already on third base. First, Johnson is an utterly engaging megastar, beloved enough that he can lead several films yearly and not overstay his welcome. His last film, December’s “Jumanji,” is still playing in second-run houses and just topped “Spider-Man” to become Sony’s highest-grossing film ever. Second, while Johnson doesn’t come across as MIT material, he radiates a level-headed good sense that makes him plausible as a researcher studying our primate cousins. Third, Davis Okoye is a helluva cool name for a movie hero.

His present gig is overseeing the gorilla enclosure at the San Diego Wildlife Sanctuary, and the film quickly establishes him as an animal lover second to none. The menagerie’s star attraction is George, a mature albino gorilla who shares a steadfast bond and sign language chats with Davis. This odd couple heart-to-heart gets a plausible rationale later in the film, but all that’s needed to accept it at the start is the understanding that they’re tight chums. It’s not an easy notion to sell, but Johnson and his outstanding computer-generated co-star do it justice.

The interspecies friendship hits a very rough patch when a crisis at a privately owned space station sends three canisters hurtling toward Earth. One splashes down in the Florida Everglades close to an alligator, another in the Wyoming badlands near a wolf. The third one drops virtually in George’s lap. The three animals rapidly grow exponentially bigger, tougher and more aggressive, instinctually uniting to knock gigantic chunks out of Chicago.

It’s up to Davis and Dr. Kate Caldwell (Naomie Harris), a disgraced genetic engineer, to stop the raging mutant beasts amid many counterproductive attacks by the military and various private militias. The duo’s third wheel is Harvey Russell (Jeffrey Dean Morgan of the zombie drama “Walking Dead”), a macho federal special agent whose character is a cornpone cliché cleverly flipped on its head.

Director Brad Peyton handles the action chops proficiently. As Davis tells Kate before a headlong glide down a collapsing skyscraper, “It’s like riding an avalanche.” But there is no way this type of smash-athon can work without a good script. One of four writers listed in the credits is Ryan J. Condal, whose sly screenplay made Johnson a surprisingly entertaining “Hercules” in 2014. His fingerprints are on this film’s surprises, barbed sarcasm, showy good and evil characters and unexpected fatalities.

I am not kidding to suggest that “Rampage” is also very much of its moment. The key to the monsters’ growth spurts is a real-life DNA-editing technology currently under research. It promises to banish maladies by cutting them at the genetic root. But what if it were to end up making unintended changes to other parts of the genome that aren’t targeted? Uh-oh.

Along another monstrous path, I couldn’t watch the film without remembering that Dr. Frankenstein’s greatest sin wasn’t making his creation, it was not caring for it. He was an ego-driven scientist on the vanguard of technical know-how but failing at basic nurturing skills. Johnson’s ex-Marine character is every bit as much a caretaker as a fighter. At times more. You get the sense that even when he’s 30 feet tall, George regards Davis as a protective big brother.

There also are references to Johnson’s days as a pro wrestling superstar. As he gently chokes out a soldier at a base where he’s being held captive, he says, “That’s a big arm, don’t fight it.”

The movie’s overall theme is everybody cooperating in crisis and kicking back at incompetent military-industrial overlords. Underscoring that sentiment are Malin Akerman and Jake Lacy, who are oh-so-hissable as the calculating sister and imbecile brother who launched the crisis when their private space research program got out of control.

I’ve recently found it hard to take much joy in action blockbusters that build up to urban destruction of Sept. 11 intensity and beyond. “Rampage” goes to the same place, yet what happens to Chicago’s Willis Tower when it comes tumbling down plays like a zany joke. In this film, the higher you rank in an organization, the less you know what you’re doing, and the main people who are obliterated — with mock-sadistic glee — are asking for it.

This isn’t life-changing work. There’s not an unusual, arresting specific scene that stands out, no hit single. I wouldn’t want “Rampage” to become a franchise brand, but inconsequential as it is, I didn’t regret giving it an hour and 47 minutes of my time. Ride the avalanche.