What is the most played electronic game in the world? Gran Turismo? Quake? Tetris? Pokemon Gold? The answer, according to educated guesswork, is probably Snake. A simple, black-and-white puzzler played on a mobile phone. It is hard to prove this, of course. But consider the facts: it took Nintendo 10 years to sell 100 million Game Boys whereas Nokia sold 128 million handsets last year alone. And then look around the train-carriage and see for yourself how many fingers are twiddling across phones that are otherwise not in use.

The amazing rise of the handset as a gaming device has put the video games industry in a flap. In 1998 the notion of gaming on a phone had not occurred. By last week it was a big enough deal to warrant its own exhibition and conference.

Mobile Entertainment 2001 in Paris was a fascinating showcase for this embryonic industry. The first thing that struck, however, was just how different it is from the "conventional" games business. There was no razzmatazz here. It is hard to justify pole dancers and Ferraris when your roster of games includes draughts and hangman.

But it is the simplicity of the "products" that has got everyone so excited. They appeal to everyone. Around 40 million people in Britain own a mobile and that includes women, the over 40s, teenage girls - all those groups that conventional video games cannot reach.

At present the size, grey colours and graphical resolution of handsets limit what can be done technically. But there are social restrictions to bear in mind, too. A good mobile game should be dipped into for five minutes at a time. It should also have a community element.

Mr Chris Wright, business development manager of the Scottish mobile games company Digital Bridges, sums it up: "Wireless games should be competing with the crossword, not Quake. People will never sit for hours playing a game on a phone," he says.

That is why the games on demonstration at Mobile Entertainment 2001 included simple golf simulations, football management, parlour games and quizzes. The latter proved the most interesting with Finland's Codeonline, one of many Nordic developers attending, previewing Who Wants To Be A Millionaire? and Trivial Pursuit. Millionaire has already been introduced in Finland and will appear on a small screen near you later in the year.

It is easy to see why these major brands would want to hijack the handset. It gives fans a chance to buy into the phenomenon, form communities around them and thereby prolong their appeal. Indeed Riot-E, another Nordic studio, has signed the mobile rights to Marvel and even Bridget Jones's Diary.

The community element in these games is critical. Crushed by 3G debt, the phone companies know that handset entertainment will only make them money if it involves sending data. Solo Snake does not earn anyone cash. Playing two-player hangman or posting Millionaire high scores in an SMS does. The French developer In Fusio embedded simple puzzle games on France Telecom handsets. Users can play them offline and then compete for prizes by posting their progress by SMS, which costs 10p. Hundreds of thousands regularly compete.

More typically, however, the networks simply host games (if you have a WAP connection, go to games on the screen menu) and tempt users to play them online. And as technologies such as general packet radio service improve data transfer rates, the hope is that games will move on to full-colour action.

In the meantime, we can look forward to the first Star Trek game on a mobile. Star Trek First Duty will be introduced later in the summer - an important release even if it does show that this new market can't quite shake off its nerdy roots. There has already been a request to translate the game into Klingon.