Former WWE wrestler Dwayne Johnson is making quite a name for himself on the big screen with silly CGI-filled action spectacles like “San Andreas” and “Jumanji.” (His less effects-laden comedies haven’t fared nearly as well at the boxoffice.) “Rampage,” the latest, is loosely based on an old video game, and though dumb as a box of rocks, it will probably appeal to the same audience that found his previous comic-book-like movies satisfying adrenaline-delivery vehicles.

As scripted by a quartet of writers, “Rampage” is basically a boy-and-his-dog story, though in this case the boy is heavily-muscled Davis Okoye (Johnson), an ex-Special Ops guy and anti-poacher activist who is also, implausibly enough, the chief primatologist at a San Diego California preserve. Having witnessed all sorts of human misconduct in his previous jobs, he now prefers animals. His best friend is George (played in motion-capture format by Jason Liles), a rare albino gorilla he saved from poachers in Rwanda (“They shot—and missed. I shot back, and didn’t,” he explains). George is as close to human as can be: he can’t speak, but he signs; and he has a wicked sense of humor, chortling over his own jokes. (And since Aristotle said man is the only animal capable of laughter, that must mean George is human.)

The Davis-George bromance is threatened, however, when the latter is unlucky enough to come into contact with a bit of space debris that’s fallen from an orbiting laboratory that exploded during an onboard crisis, killing scientist Kerry Atkins (Marley Shelton). The station was owned by the Energyne Corporation headed by siblings Brett Wyden (Jake Lacy), the goofy one, and Claire (Malin Akerman), the evil one. The work being done on the station involved genetic engineering of an illegal sort—Project Rampage, which apparently involves turning animals into huge, fearsome weapons.

Atkins was able to jettison three samples of the formula before going down with the ship, and they land in different locales: California, where curious George is infected by it; Wyoming, where the substance alters a wolf that attacks a mercenary team sent by Energyne to retrieve it (the team is led by ultra-macho Joe Manganiello, who serves the same function here that Steven Seagal did in “Executive Decision,” if you can remember that far back); and the Florida Everglades, where an alligator is affected.

After George, growing exponentially, goes a bit bananas, federal troops are called in under the direction of Harvey Russell (Jeffrey Dean Morgan). By this time Davis has reluctantly joined forces with Dr. Kate Caldwell (Naomie Harris), a geneticist who once worked on Rampage at Energyne but tried to derail the project, winding up with a stint in prison for her efforts. When Harris tries to transport George, Davis and Caldwell to a security facility, all hell breaks loose and the three humans are left struggling to reach civilization after George has run off.

Where is he headed? Why, to Chicago, of course; the headquarters of Energyne is in the city’s tallest building, the Willis (nee Sears) Tower, from the aerial atop which Claire has set off a signal to summon him, as well as the unnamed wolf and alligator. Her purpose is apparently to extract from them a blood sample that will allow the company to replicate the transformative formula.

While the military, under tough-as-nails Colonel Blake (Demetrius Grosse), prepares to destroy the huge creatures with its battery of artillery—and, if need be, bombs—Davis, Caldwell and Harris race to Illinois to confront the Wydens and secure what Davis and Caldwell assume is an antidote the corporation must possess.

Naturally what results is destructive chaos in the Loop as the beasties take on the army and rip apart much of the urban landscape on the way to the Tower. (Actually the geography is off: they appear to be headed north on Michigan Avenue when the Tower is far south. But the Chicago River Bridge is certainly a stunning enough landmark that the makers should have wanted to include it.) George does eventually make it there, managing to intervene in the confrontation between the Wydens and our heroes atop the building, and to join Davis in battling the other two beasts after the antidote has taken effect. One is happy to note that amidst all the mayhem, the video-game cliché of immediate resurrection occurs not once but twice. Most notably, it’s employed when Davis is shot and crumples to the floor, only to reappear shortly afterward to announce that the bullet had missed all the “vital organs.” He then proceeds to indulge in typically Johnson-esque acts of physical abandon that suggest the slug had about as much effect on him as a wiffle ball.)

Need we add that the world is saved, though a good deal of downtown Chicago is left in rubble. (Among the places shown being destroyed is a Dave & Buster’s—do companies actually pay for this sort of product placement?)

All this malarkey is presented in garish comic-book style, the mayhem—done up with uneven CGI—punctuated by juvenile bits of humor. Probably the most successful comedic tone is struck by Morgan, the maniacal Negan of “The Walking Dead,” who makes Russell a grinning, aw-shucks good ole boy who steals every scene he’s in. By contrast Johnson is just his usual stalwart self, but still a naturally ingratiating presence, and George—“acted” in Andy Serkis style by Liles and done up in some of the best work the effects team has to offer—proves a good foil for him (far superior to Zac Efron in “Baywatch,” for sure). Harris is a nice addendum to the pair, and though Akerman and Lacy overdo, respectively, the malevolence and the goofiness of the Wydens, that’s the way with comic-book villains. Technically the movie is solid if not quite top-drawer in the effects department, particularly in the final act.

It’s the faintest of praise, but you could say that “Rampage” is one of those empty-headed, CGI-laden popcorn extravaganzas that aims low but hits its admittedly trivial target. Thirteen-year old boys, and others of similar mentality whatever their actual age, will eat it up just as they did “San Andreas” and “Jumanji.”

A postscript: can we call a halt, please, to the trashing of Chicago? It’s architecturally a lovely city, which must attract filmmakers, but after the fate it suffered in “Transformers: Dark of the Moon” and now this, its skyline really deserves a reprieve from mindless destruction, though admittedly it’s kind of a charge to see the Sears Tower—sorry, Willis Tower—collapse with such impressive force.