“Boy Kills World” is a gonzo, video-game-violent/splatter-film-bloody “Hunger Games” for fanboys.

It is “Oldboy” meets “Scott Pilgrim vs. the World,” pandering and slaughtering in equal measure, a movie with jaunty, genre-spoofing possibilities that descend into into lethargy and wind-up in stomach-turning savagery before all is said and done.

And star Bill Skarsgård’s character and leading man turn is just similar enough to brother Alexander Skarsgård’s work in Netflix’s “Mute” to be worth mentioning.

Skarsgård (“It”) plays the titular Boy, raised since childhood by a martial arts shaman (Yayan Ruhian of “The Raid” movies and “John Wick 3”) who trained him in all the martial arts movie cliche ways.

The deaf-mute boy lost his family. And the fascist oligarchs who run this dystopia, , the Van Der Koys, are the reasons for his training, his motivation to succeed.

He is “an intrument built to kill Hilda Van Der Koy,” he narrates. That would be the ruthless matriarch played by Famke Janssen.

After reaching adulthood, Boy will have to kill his way through other members of the family, played by Sharlto Copley, Michelle Dockery and others, if he’s to have any prayer of fulfilling his “mission.”

The gimmick here is that our anti-hero can’t remember what his voice, when he had one, sounded like. So in his head, he narrates the story in the voice of his favorite video game hero (H. Jon Benjamin), who also happens to be a voice-over mainstay and the heart of animated series from “Dr. Katz: Professional Therapist” to “Archer,” “Family Guy” to “Bob’s Burgers.”

His intererior monologues dominate the first half of the picture, telling us bits of Boy’s back story, imagining conversations with the kid sister (Quinn Copland) he lost, a child apparition who is both his guide and his conscience.

He likes to finish his fights with a “Player One WINS.” Except when this or that “Player Two” fights back, or won’t “die.”

Copley plays a dye-jobbed blowhard, perfect as the in Face of the Family on TV. Dockery is the schemer who props him up, Bret Gelman is the violent fixer who fancies himself the screenwriter of all the TV appearances.

And fanboy fave Jessica Rothe (“Happy Death Day”)? Well, you’ll see.

The fights, with fighter, stunt-man and sometime stunt coordinator Ruhian on set and “District 9” stunt director Grant Hulley in charge, are mayhem incarnate — head-butts, fists and knives and other sharp objects thrown in with the pistol and assault rifle fusillades.

First-time feature director Moritz Mohr tries to keep this beast on its feet and fighting with its feet and hands and head and anything else. But the action falls off steeply as we drift into the middle acts, and a “team” (Andrew Koji and Isaiah Mustafa) is comically drawn in.

And the finale is so violent and drawn-out as to be excruciating, enough to make you forget the genre-spoofing whimsy of having H. Jon Benjamin ironically voice-over a sadistic and gory vengeance fantasy.

There are clever ideas and casting flourishes at the heart of “Boy Kills World.” But in execution, one keeps coming back to the phrase “Less is more,” even in a hyper-violent action comedy where the excess is kind of the point.

Rating: R, graphic violence and lots and lots of it.

Cast: Bill Skarsgård, Michelle Dockery, Sharlto Copley, Yayan Ruhian, Andrew Koji, Isaiah Mustafa, Jessica Rothe and Famke Janssen, featuring the voice of H. Jon Benjamin.

Credits: Directed by Moritz Mohr, scripted by Tyler Burton Smith and Arend Remmers, based on a short film by Mohr and Remmers. A Lionsgate/Roadside Attractions release.

Running time: 1:51