Video games for young adults, children and teens bring in $10 billion a year in the US. Certainly some of the games offer harmless entertainment and maybe even some educational value. But the gamez that seem to be the most eagerly anticipated, the games that major retailer Zany Brainy says "the industry is focusing on," and the games that fly off the shelves as soon as they're released are those rated "M" for mature and "AO" for adults only.