There's a scene about 25 minutes into Doom when the genetic archaeologist played by Rosamund Pike is dissecting mutant corpses in her besieged laboratory on Mars - everyone should have a hobby - and she swivels to address one of the marine commandos transported from earth to lock down the facility. She declares, in that sultry baritone grown men love and small children fear: "Whatever it is, it's stripping our DNA and I have no idea what it's changing us into." Which is the moment, I'm afraid, I surrendered, slumped in my seat, turned to my companion and moaned, "Oh dear God, please let it be actors."
He laughed. You shouldn't. For the real - and possibly insurmountable - problem with movies adapted from video games isn't any lack of acting but rather the irritating excess of it. We tend to think of these big Hollywood sci-fi fantasy shoot-'em-ups as the height of exploitation and cynicism - based on a video game, indeed - but the truth is the genre couldn't be more sentimental or out of touch in its belief in such sudden redundancies as motivation, character and relationships, not to mention story arc, plot development, closure and all the other traditional satisfactions of mainstream cinema. The Doom script-writers have fabricated a childhood trauma for their hero (Karl Urban) and the preview audience I saw the film with quite rightly greeted this passe invention with jeers and eye-rolling contempt. They weren't buying Pike as the token "romantic interest" either. Violence was what they'd queued for, not sex. Pike is simply there to establish heterosexual bona fides amid a sweaty atmosphere of back- slapping homoeroticism. And who's to blame the Doomkopfs? The Xbox generation are hard-wired to win, and recognise old-fashioned cant when they see it: yes, you may have your mayhem but you've got to pretend to care first. If you're a gamer - and there are more gamers now than movie-goers - emotion is merely something that gets in the way. Feeling is that embarrassing thing stopping you from reaching the next level. Empathy is worse than an obstacle; it's irrelevant.
This is just as well. Imagine how un-bearable it would be if we actually did care about characters about to be slaughtered wholesale. There's a guy here who becomes molecularly fused with his wheelchair after turning into what looks like a drug dealer's dog and, sure enough, the sequence is played for kicks. I felt middle-aged and middlebrow for recoiling, but then I'm a 20th-century boy, raised on movies and rock'n'roll, and that's so totally over, dude.
Video games and vainglorious rap are pop culture's new lingua franca, and the brutality integral to both is at the same time overwhelming and weirdly weightless. Small wonder the Doomkopfs cheer when the last ten minutes of the film revert to FPS (first-person shooter) and the camera-cum-joystick starts to blast zombies, imps, barons and various hell knights. The film was finally being honest about what its target demographic wants. Bang bang.
This ought to be where the better informed raise the statistical fact that most video games revolve around construction and co-operation, and point out how regular practice improves hand/eye co-ordination in teenagers, incredibly useful if your child intends either to be a jet pilot or to masturbate for a living. To which I can only sigh and reply: show me the movie based on SimCity.
The video games transferred to cellu-loid are entitled Street Fighter, Resident Evil, House of the Dead, Mortal Kombat and Wing Commander, and Hollywood has been getting the hybrid wrong since the disastrous flop of Super Mario Brothers in 1993, when Bob Hoskins and John Leguizamo brought unwelcome layers of insightful depth to their roles as Italian plumbers trapped in an alternative dimension ruled by Dennis Hopper (don't ask). Doom certainly doesn't make that mistake. How could it, when its leading man is called The Rock, a monicker that itself answers probably the most frequently asked question about the ex-World Federation wrestler: is he animal, vegetable or mineral?
It's the picture's great luck that at no point does The Rock ever appear even remotely human, but rather carved from a hundredweight of doner kebab and then lovingly polished with Lemon Pledge by a troupe of gay elves.
The Rock is for people who find Vin Diesel too intellectually stimulating, and he not only belongs to this particular universe, he takes the curse off it, too. His tattooed, tough-talking Sarge is a cartoon to begin with, and how can you hurt or kill a cartoon? When he's bitten and turns evil, he's no different from when he was good, except his enunciation improves. With The Rock around, lines such as, "Let's see if we can find a body to go with that arm" seem genuinely witty. In The Rock, special effect and action figure fuse, no acting required.