Since its launch in 2005, Nintendo's Dr Kawashima's Brain Training has sparked a market phenomenon. According to Nintendo the title, along with its sequel More Brain Training from Dr Kawashima, has sold over 30 million units worldwide, accounting for one in every five DS games purchased.
Such is the success of the Brain Training (or Brain Age in Japan/US) titles, they have become almost synonymous with the company's successful strategy to harness the spending power of casual gamers. With the help of Nicole Kidman and Patrick Stewart, Brain Training has vaulted the DS into new demographics, bringing consoles to the hands of people who would have once eschewed anything containing so much as a microchip.
Wii Fit also caters for this self-improvement market and has met with equally spectacular sales. But while few would question the benefits of games encouraging physical activity, the merits of brain training are not so clear-cut - here, in the second of a two-part series on games and health, Alastair McQueen puzzles over the research.