The demi-paradise: Martin Plimmer explores the zombie delights on offer at London's neon Segaworld

Like nature, the Trocadero abhors a vacuum. Unlike nature, it fills it with oversize TV screens, popping strobes and more noise than you can properly accommodate with only two ears. If you walked through the Trocadero shouting through a megaphone, wearing a neon hat, nobody would notice you.

Six floors of this roaring building are sub-let to Sega, and filled up with fighting and racing video games, along with six rides and a stall selling donuts and frozen slush (the preferred food of sonic hedgehogs). The machines stand in clumps, baying for human attention.

They are looped to the death, obsessively replaying the same dizzying Formula One circuit, or 24-stone virtual Sumo wrestler hitting the cyberdeck. Despite this frenzied screen activity, Segaworld is oddly static, full of motionless, wall-staring youths, like men at urinals.You wonder, as you watch them industriously blowing the limbs off challengers, whether this is an invaluable safety release for potential Klaus Barbies, or whether it merely nurtures them.

The waves of zombies which come at you in House of the Dead are not so inconsiderate as to bother you with moral questions. Instead, they pose obligingly for their deaths. If you run out of lives before they do, they stop the merciless attacking and wait politely for you to feed the machine a pounds 1 coin. If you shoot one, he goes uncomplaining into a death sub-routine he's done many times before. He knows the routine.

It's a pretty routine place. There's not a gleam of humour in Segaworld; not a virtual smile that isn't grim. Everything is explicitly realised on screen for you. Your human contribution is to learn the machine's routine as fast as possible and thereby master it.

If a thing is technologically feasible, goes the Sega ethos, then that's reason enough to do it. They haven't yet realised that to make it live, you need imagination. Please God don't let them crack the computer code for that, or we'll all be in their thrall.

The sight of two boys in Arsenal shirts playing football in the gloom, by feeding pounds 1 coins into a machine and twiddling buttons, is one to make Danny Blanchflower turn in his grave. I wanted to take them aside, and tell them about playing fields and fresh air.

One hour in Segaworld and you wonder which of you is the zombie. While undergoing the Space Mission ride, in a bucking chair, wearing a primitive virtual reality headset, trying to gun down blurred enemy spacecraft (pounds 3 a go), I suffered a wave of excruciating nausea and had to look down at my legs, which I reckoned were being reassuringly still. They weren't my legs! They were virtual legs, and they were wearing a Japanese artists's representation of my trousers.

I closed my eyes and drifted into a fantasy of my own at that point. I was standing in Segaworld holding a real gun. It was quite clear - that's the advantage of imagination: better image resolution. I had a hostage Tamogotchi there. "Stop the machines," I shouted. "Or the Tamogotchi gets it!" I fancied the tabloid headlines: "Gotchi!" I smiled grimly and pulled the trigger.