Television advert breaks are now full of children playing with radio-controlled cars, anorexic dolls that cry crocodile tears, short-range projectile weapons and robots, so Christmas is officially on its way. But the manufacturers of conventional toys (cue misty-eyed thirty-somethings reminiscing about Top Trumps and Star Wars figures) are fighting a tough rearguard action against computer-based entertainment.

The computer games industry is, allegedly, worth more than Hollywood. That statistic is frequently bandied about with no qualifier, and you'll get none here either, but it sounds plausible. Sony, Nintendo and Sega are fighting tooth and nail to sell you their cheap gaming hardware, so that they can reap the rewards of high-margin software sales, and the PC entertainment market has a pretty respectable turnover too. That's leaving aside the millions of pounds poured into arcade machines during rainy weekends in Skegness. Why are computer games becoming so incredibly popular? Because they're now so detailed, so totally immersive and so accessible that they're often far more exciting than real life. Forget ecstasy and cocaine; silicon is the new designer drug (sorry).

Nobody understands the addictive qualities of computers better than the Japanese. They started it with Tamagotchi, the 'virtual pets' that were nothing more than crude LCD graphics and simple algorithms, yet somehow managed to convince millions of people worldwide that they were cute, sentient life-forms. And, although some very clever artificial intelligence products have appeared in this country (click here for an example), it's the Japanese who have done it again this year. Nintendo's Pokémon is cleaning up all over the world, absorbing pocket money like some sort of... giant pocket money absorption thing. According to a recent press release from Nintendo, Pokémon is now the most searched-for word on the Internet, beating the perennials such as sex, porn, Microsoft and more sex. It's brilliantly designed to appeal to the real money-spenders in every household, and it's worked a treat. If you don't know what it is, search for it...

Science Fiction writers have frequently toyed with the concept of a computer game so realistic that players prefer it to real life; the idea has been moulded into programmes and films as diverse as Red Dwarf and, with a bit of a twist, The Matrix. There are no obvious technical reasons why it shouldn't happen, either. We already know enough about the biochemistry of the brain to understand the effects of recreational drugs, and it's many years since scientists first fitted electrodes to a living rat's brain, encouraging it to repeatedly press a button by stimulating its pleasure senses electrically.

Skipping blithely over the ethics question, it's a relatively small step from a rat's brain to a human's. Imagine a version of Quake or some other 3D action game that sent pleasure signals to your brain whenever you killed an opponent, and pain signals when you yourself were injured or killed. Now replace the monitor with a VR headset projecting images directly onto your eyes' retinas, while you float in a suspension tank to remove any other stimuli. Theoretically this could all be done now, and although stimulating the brain directly to produce a totally different perceived environment is a little beyond science at the moment, developments in nano-technology might take us pretty close in the next century.

It's a far cry from Grifters and Space Invaders, isn't it?