HERE IS A tip to help you with the plot of the upcoming film Super Mario Bros. The mushrooms are friendly because they are outcrops of the fungus into which Princess Daisy's father was turned by a process of de-evolution invented by the surprisingly human-looking descendants of the dinosaurs that were separated from our world by a meteorite strike in Brooklyn 65 million years ago. Simple.

Unfortunately, if you also want to know why Koopa - played by the incomparable Dennis Hopper - and his cohorts do not get rid of the fungus, why replacing the fragment of meteorite will rejoin the two dimensions, what Daisy's father was doing among the dinosaur descendants in the first place, why or how the fungus periodically produces little bombs that walk, what caused the rock partition between the dimensions to turn liquid or, indeed, almost anything else about this strange and noisy movie, then I can be of no assistance. The answers are, I am sure, in there somewhere, but I missed them.

Your children will not, in any case, be troubled. They will either know the answers beforehand or, more likely, they will so uncritically accept the film's logic that they will not notice the questions. For, if you are going to see the film at all, the probability is that yours is one of the 25 per cent of households with children that has a computer games system. And all the weirdness of Super Mario Bros is explained by the fact that it is a film whose plot, imagery and style are generated entirely by those strange types who write computer programmes.

The Mario Brothers were created as the heroes of a series of Nintendo games. As such they embody the curious, hybrid sub-culture of this business. The hardware for these systems - primarily from Nintendo and Sega - is Japanese. But the Japanese have a problem with the software. They do not have a library of images guaranteed to work in any country in the world. Only the Americans, thanks to film and television, have that.

So computer games are full of American imagery: Hollywood films are translated directly into games, violent street battles are fought in what appears to be the Bronx of South-Central LA and the Marios are plumbers from Brooklyn. Games produced without such clear, cultural anchoring stray far into the downright weird, springing either from pure, crazed fantasy - Sonic the Hedgehog - or from imperfectly digested fragments of European mythology - Golden Axe. The imagery is the result of a frenetic and voraciously indiscriminate search for some story, any story, to attach to the abstract shimmerings of the electrons.

Adults, accustomed by upbringing to noting narrative and context, will be at a loss - everything seems so arbitrary, so detached from sense. But children will understand at once that it is the quality of their interaction with the material that counts, story and imagery are secondary. They are as happy to identify with a Brooklyn plumber as with a Norse God.

Those adults prone to moral panic - I am one - will feel alienated and alarmed by a cultural form so bizarre, unprecedented and imperiously energetic. What is this mad, transnational salad of, usually, violent imagery doing to our children's brains? Will they grow up thinking life is a matter of grabbing mushrooms and tossing bombs? Perhaps, now, it is.

Furthermore, playing the games is a lonely, obsessive activity, involving the total suspension of all normal life functions. While conscientiously researching this column, I idly picked up a Nintendo Game Boy to play Dr Mario, an abstract puzzle with a perfunctory medical theme that involves lining up capsules to destroy 'viruses'. Four hours later I emerged to find it was night, my neck had locked, my legs were without blood. Yet even writing that sentence made me want to go back and have another go. It was not enjoyable, it was merely necessary; I was not happy doing it, but for a brief period under the game's spell, I could not be happy not doing it.

Unsurprisingly, this intense, sweaty, addictive quality has made computer games into very big business. The total hardware and software games market in this country is now worth pounds 900m. The companies reckon they can continue to grow by increasing their penetration of households with children from our 25 per cent to the US level of 40 per cent. After that they target the adults. We shall have been softened up by the fact that, since the games now have a history in our lives of around 15 years, anybody up to 40 will be used to them. But, to soften the blow, the games will soon be included in complete 'Home Entertainment Systems'. You can fool yourself into thinking you are buying a television and hi-fi, but then, oh whoops, here's that nice Dr Mario again to kill time while listening to Brahms.

On top of that, Sega is starting a series of arcades to house the highest games technology and, of course, for at least the next five years, there will be a constant stream of new technologies to buy for the home. Virtual Reality goggles will soon strengthen your conviction that the machine you idly admitted to the house last Christmas has destroyed your child's mind.

Two themes underlie the moral panic response to all this: addiction and unreality. Academic work in Glasgow suggested that 6 to 10 per cent of children exposed to computer games became addicted in the sense that they spent all their free time and all their money playing or buying the games. This sounds terrible but, in truth, all children are prone to addiction - to music, clothes, train-spotting, television or whatever. The intensity of the involvement is invariably alarming, but it is usually dismissable as 'a phase'.

But, it will be said, computer games are different - this is where the unreality comes in. The games are lonely and antisocial. Unlike clothes or music or even the narrative myths of television, they do not provide any sense of the way the world works. Their whole aim is to remove the player into a different world and, once there, he is engaged by a purely mechanical logic that has no bearing on what his parents may still be nave enough to call the 'real world'.

Of course, television does something similar, but Ian Brown, a psychologist at Glasgow, suggests, in a rather sinister comparison, that the difference between computer games and television is like the difference between crack and cocaine. One involves total engagement, the other can still be kept at a kind of recreative distance.

Moral non-panickers, such as Leslie Haddon of Sussex University, are sceptical. The isolation of the games is only at the moment of playing. In reality this act is embedded in a youth culture as substantial and cohesive as that of pop music. Look at the magazine racks: there are dozens of publications for games-players. They may be uniformly illiterate and revolting, but those Beatles and Stones fanzines weren't exactly Proust either.

In any case, the history of moral panics, which Dr Haddon has studied, is scarcely respectable. In the mid-Eighties, he points out, one Labour MP tried to put through a Bill controlling Space Invaders - how quaint, like trying to outlaw the Hula-Hoop. The overall wisdom of the anti-panickers is that adults in general have always thought the behaviour of their children was a portent of the apocalypse; in reality, it is just the usual revolt of the generations.

In fact, this is not true. It was only among the first post-war generation that children grew up with the conviction that they were destined to be fundamentally different from their parents. This hardened into the conviction that they were obliged to be fundamentally different and this obligation was reinforced by vast commercial interests, all of which had targeted youth as the growing market. From the mid-Fifties onwards the idea that young people would inevitably revolt by creating deliberately alarming, anti-adult sub-cultural forms of dress and entertainment was glibly and very unhistorically embraced as a kind of law of nature.

The reality was that commercial interests were kidnapping children by telling them that their parents were stupid. It happened initially because we became richer and therefore freer of dependence on the family base and, later, because the expansion of new technologies offered an apparent infinity of new possibilities for entertainment. New things were more fun, change was always for the better and, hey, chill out, it's going to happen anyway, so why not go with the flow?

Computer games are the high point of these developments. Technological determinism convinces us that they are going to happen anyway, and impotent acceptance of the perpetual difference of youth justifies these private worlds of fantasy, violence and myth. But they are not like the Hula-Hoop, they do change things. Primarily they do so by elevating a consumer product to a system of intense and exclusive involvement. You can buy something that can take over your life and remove you from this world into another characterised by an entirely disconnected and inhuman logic. They are a portent of a world that has no need of connections or 'reality', a portent of a loss of control amid the hypnotic systems of consumption.

There is no alternative: I shall play Dr Mario one last time and then I shall panic.