Maybe if you haven’t seen “Aliens,” you’ll be able to enjoy this ultra-chintzy ripoff of the 1986 blockbuster, in which a character called Reaper (played by Karl Urban) may be taken as the replacement for Sigourney Weaver’s Ripley–not precisely a fair exchange. After nearly two decades James Cameron’s picture remains a rip-roaring thrill ride that wears its years lightly. By contrast “Doom” is a damp squib indeed. Just call it “Aliens for Dummies”–dark, murky, loud, gory and incredibly dull.

Well, maybe that’s an unfair criticism. “Doom” is based, after all, on a video game–a fact director Andrzej Bartkowiak and cinematographer Tony Pierce-Roberts make abundantly clear near the close in a scene shot from the POV of Reaper stalking and blasting his prey down a series of hallways, obviously putting the viewer in the position of the player in the game. But the movie is still an “Aliens” clone one step removed, because from what happens in the script by David Callaham and Wesley Strick, the video product must have been a copy of Cameron’s movie. And to be fair, the game might be enjoyable. As the movie amply demonstrates, though, as a spectator sport it certainly is not.

The plot of “Doom” is almost unbelievably simple. Sometime in the future, a unit of gung-ho Marines is “beamed up” to a scientific research station on Mars, where an archaeological dig has apparently unearthed some monsters that are wiping out the staff. The team is led by brawny Sarge (Dwayne “The Rock” Johnson) and includes a collection of equally cardboard figures: Reaper (Urban), a sensitive soul whose estranged sister Sam (Rosamund Pike) just happens to be one of the station scientists (it happens that their parents died there years before, you see); a callow kid on his first mission (Al Weaver); Portman (Richard Brake), a trouble-making whiner with a dirty mind and dirty mouth; Goat (Ben Daniels), a Jesus freak; Destroyer (Deobia Oparei), a tough black dude; and Duke (Raz Adoti), a hip black dude. For ninety endless minutes or so we watch the guys wandering through tunnels that look like an abandoned sewer system, frequently blasting away at what appear to be humanoids with skin the consistency of cooked pizza and a nasty attitude, and–of course–occasionally being dispatched by them. (It isn’t hard to predict who will die and who will survive.) There’s the wisp of an explanation for all this, having something to do with unauthorized experiments conducted by mad scientist Dr. Carmack (Robert Russell) that result in human mutations; but mostly what the movie consists of is an hour or so of stalking followed by another of chases. Presumably to satisfy Johnson’s wrestling fans, the last act features Sarge’s transformation into a sort of well-muscled Captain Queeg, maniacally intent on exterminating every survivor of the station before they can return to earth and perhaps spread a contagion, and Reaper’s principled opposition to him–leading to a mano-a-mano confrontation with plenty of well-choreographed takedowns and extravagant grunts and groans. Unfortunately, the pummeling goes on for so long–with sound effects and crashing music added to enhance the in-your-face mayhem–that before it’s over it’s the viewer who feels like tapping out.

If “Doom” is utterly threadbare from the story standpoint, it’s no better technically. The sets look like the underground tunnel complex that’s appeared in every other video game movie (and tunnels being tunnels, they can be used repeatedly though the locations are supposed to be different), and the special effects are thoroughly mediocre. In terms of creature design, the pizza-men are bad enough, but toward the close we get a different model–though it seems to have been created in the same way as the others: a bulbous, mushy thing propped up on a motorized wheelchair and looking rather like an asymmetrical bean bag with eyes, tiny little claws and a nasty set of teeth. It would have been nice to see somebody kick it aside like some diseased soccer ball, but that doesn’t happen.

Nonetheless the non-human performers are better than the real ones. As his previous movie have shown, Johnson has potential as an action star, but here he’s stymied by the requirement to act obsessed and intense–something that seems beyond his range at this stage in his career. Urban looks bored and passive, perhaps intending to show viewers the proper attitude for them to adopt. And Pike isn’t remotely convincing as a brainy scientist. As for the other members of the Strike Team, the performers all overdo things with such abandon that even in the gloomy, refuse-filled environment they’re wandering through, the stench of ham is overpowering. (These guys are also the worst shots in the world: just call them the Keystone Marines.) To complete the unhappy list, Pierce-Roberts’ photography emphasizes darkness and shadows to such an extent that it’s often impossible to discern exactly what’s going on.

Of course, with a movie as terrible as “Doom,” that’s not entirely a bad thing.