The commission sent 13- to 16-year-old undercover shoppers into various establishments to see what they could get away with. Only 20 percent were able to buy unrated games, a big drop from 42 percent in a 2006 survey. By contrast, 35 percent of the shoppers were able to sneak into R-rated movies.

GameStop and EB Games had the best record overall, rejecting 94 percent of underage video-game buyers. That kind of effort could quiet calls for legislation, recently introduced in the House, that calls for fines for retailers who don't check buyers' identification.