If you want to know what is happening in the mind of the average teenage boy you must follow the action of his thumbs, because the eager digits that might once have flicked through the pages of Hotspur or Penthouse are now more likely to be employed in a fight against universal evil in one of its modern guises. Last year saw the greatest ever increase in sales of computer games, to the point where the world's biggest titles - Halo 3, for example - reliably bring in more cash than most blockbuster movies. In small bedrooms throughout the Western world, boys in woolly hats and Nike trainers are currently tackling the most intractable problems of the day, and it seems their arsenals are unlimited and their thumbs tireless.

LRB 24 January 2008 | PDF Download