But a new wave of games is turning the cliché on its head.

Nintendo has sold nearly five million copies of its three Nintendo DS brain training games since the series launched in Japan a year ago.

The first title in the series, Dr Kawashima's Brain Training: How Old Is Your Brain?, sees players follow a daily regime of brain-enhancing exercises and is due to be released in the UK in June.

Dr Kawashima's Brain Training comprises a variety of mini-games designed to give brains a workout.

Activities include solving simple maths problems, counting people going in and out of a house, drawing pictures on the Nintendo DS touchscreen, and reading classic literature aloud into the device's microphone.

Players are given a brain age reflecting their performance. Over time, your brain age should get younger as you achieve better scores. ------Smart thinking -------------------

Dr Kawashima's Brain Training has sold some 1.8 million copies, and it is still in the Japanese top 10 a year after release.

But the brain training games' success is down to more than just a neat gameplay gimmick.

Unlike Nintendo's fictional creations, such as Donkey Kong or Mario, Dr Kawashima really is a leading Japanese brain expert.

A graduate of the Tohuku University School of Medicine, Dr Kawashima works at the same university's New Industry Creation Hatchery Centre, and is one of the country's top researchers into brain imaging.

He is also a best-selling author. His two books on brain training have sold more than a million copies in Japan.

Nintendo's President Satoru Iwata personally shepherded the idea of a brain-enhancing game through production.

It originally arose from a remark by a member of Nintendo's board of directors that he knew nobody his own age who played games.

And Mr Iwata sought Dr Kawashima's involvement, seeing the two men's similar fifty-something ages as common ground.

It is all a long way from a typical video game's development, and the differences continue in the older, non-gamers that Nintendo is explicitly targeting with the title.

Dr Kawashima's Brain Training will be the first video game ever to be advertised and featured in Saga magazine, for instance.

"As these new types of games gain in popularity, we must find new and different ways to bring them to new audiences, many of whom will have never played a traditional videogame before," explained a Nintendo spokesperson. --------Mobile mindset-----------------

Nintendo has not got a monopoly on brain training games, however.

Mobile phone developer Upstart Games is creating IQ Academy, a reworking of the Japanese mobile title Right Brain Paradise, which has been a big hit in Asia. think we have a critical mass of people that have been exposed to games for the last 25 years, and there is much wider acceptance of games as an entertainment medium

IQ Academy gauges the player's performance in various tasks of recognition, logical prediction and spatial resolution.

It then rates the player and mixes up the puzzles offered next time, promoting further improvement.

Whereas Nintendo's games use the DS's stylus and touchscreen, IQ Academy employs a simple multiple choice system.

"The nice thing about IQ Academy is that it doesn't require any specialist hardware to work," said Barry O'Neill, CEO of Upstart Games. "Almost anyone with a mobile phone will be able to download and play it."

Mr O'Neill said there is a definite "halo effect" around brain games thanks to Nintendo's titles.

But he added that it is the broadening games audience that has really made such games more feasible.

"I think we have a critical mass of people that have been exposed to games for the last 25 years, and there is much wider acceptance of games as an entertainment medium," Mr O'Neill said.

"Not everyone wants to play first-person action titles or role-playing games," he continued. "Games that can challenge you from a mental perspective without falling into a gamer genre cliché are proving very popular."