Florence Cohen, 85, of New York, said in the lawsuit filed in U.S. District Court in Manhattan that the game's manufacturer, Rockstar Games, and its parent company, New York-based Take Two Interactive Software Inc., engaged in false, misleading and deceptive practices.
She sought unspecified damages on behalf of herself and all consumers nationwide, saying the company should give up its profits from the game for what amounted to false advertising, consumer deception and unfair business practices.
Cohen said in the suit that she bought the game in late 2004 for her grandson when it was rated "M" for mature, for players 17 and older. According to the suit, she directed that it be taken away from her grandson, which was done.
The game was released in October with an "M" rating. After a storm of negative publicity about the hidden scenes, the Entertainment Software Ratings Board, an industry group responsible for rating games, changed the rating to "AO" for adults only.
Laurence D. Paskowitz, the lawyer who filed the lawsuit on behalf of Cohen, said no parent would knowingly buy an adult-only video game for their children.
"They should really make sure this doesn't happen again," he said. "The least this company can do is offer refunds."
Hidden areas in video games that can be unlocked with special codes or modifications are not uncommon.
Take Two Interactive initially said the scenes were not part of the retail version of the game but later admitted they were.
A message left for a company spokesman was not immediately returned. On Tuesday, Take-Two announced that it had been notified by the Federal Trade Commission's Division of Advertising Practices that it was conducting an inquiry into the game's advertising claims.
The company said it planned to cooperate fully with the probe.
"Rockstar Games and Take Two Interactive regret that consumers may have been exposed to content that was not intended to be accessible in the playable version of `Grand Theft Auto: San Andreas'," it said in a statement.
The company said it had halted production of the game in the controversial form and was working on a version of the game without the hidden sexual content.
"Going forward, the company will refine the process by which it edits games and will enhance the protection of its game code to prevent such future modifications," it said.
Earlier this week, the House voted 355-21 for a resolution asking the FTC to investigate the company. Last week, Sen. Hillary Rodham Clinton, D-N.Y., asked the FTC to investigate Rockstar, saying the company had "gamed the ratings system" by concealing sex scenes in the game that can be unlocked by computer programs available on the Internet.
Wal-Mart Stores Inc., Target Corp., Best Buy Co. and Circuit City Stores Inc. have pulled the game - last year's top-seller among console games - from their shelves following the rating change.