A substantial minority of American adults would rather spend their free time playing casual games - such online diversions as Bejeweled and TextTwist - than watch television.

A study by Harris Interactive set for release Monday found that 31 percent of the over-18 set preferred the games to TV for whiling away a spare hour. Watching movies at home fared better, with 21 percent choosing games instead, but going to the movie theater did slightly worse with 35 percent.

RealNetworks commissioned the study to understand its customers better, company senior vice president worldwide games Michael Schutzler said. He added that they were very surprised by some of the findings, particularly when the report broke out the numbers for women older than 40.

Nearly half (49 percent) would play casual games rather than go to the movie theater, 32 percent opted for them over movies at home, and 37 percent chose them over watching TV.

Schutzler said RealNets began offering games six years ago. It really wasn't going well, he added. Then just for the heck of it we tried 'Bejeweled.' It immediately sold hundreds of times anything else we ever offered.

Working with women's lifestyle expert Jennifer Louden, RealNets used the Harris findings and other research to improve sales of advertising and downloaded games.

Effective advertising in casual games requires an added level of sensitivity, Schutzler said. It's clearly an effective way to reach this important audience, women over 40, but it can't disrupt the experience.

The same group doesn't like games that incorporate brands into the action, often called advergames, but the set reacts positively to sponsorship and to interstitials between levels, he said.