Working out of a Highlandtown studio, Ben Walsh and his small team of video game developers recently created My Pet Rock, a family-friendly Facebook game.

But, Walsh said, some day he might decide to design a video game for a more, er, mature audience — and he's heartened to know the Supreme Court now has his back.

In a landmark case, the high court on Monday struck down a California law barring the sale or rental of violent video games to minors. The 7-2 decision gave video games the same First Amendment protections afforded books, plays and movies.

The decision was cheered across the country by video game companies, including those in the Baltimore area.

"I'm happy about the ruling," Walsh, chief executive of Pure Bang Games, said Monday. "My biggest concern is the slippery slope that the California law represented. Once you start saying what is allowed, what is not allowed, it can spread into movies and comic books and other forms of art."

The Supreme Court decision was the culmination of a decade-long battle in the courts between the video game industry and opponents who sought to restrict its influence on minors.

The industry has won a dozen battles in lower courts, but the case of Brown v. Entertainment Merchants Association was the first time the Supreme Court had weighed in.

The industry has long said its self-policing efforts, including ratings by the independent Entertainment Software Ratings Board, are sufficient to help parents monitor their children's use of video games.

"This is a historic and complete win for the First Amendment and the creative freedom of artists and storytellers everywhere," said Michael D. Gallagher, president and chief executive of the Washington-based Entertainment Software Association, which represents video game companies, in a statement.

The decision will allow video game developers to freely pursue their projects in an increasingly lucrative business, industry observers say. Many designers and programmers view their work as creative activity deserving of constitutional protections.

If the California law were allowed to stand, "you would be limiting what people can do in a game," said Gabriel Pendleton, communications manager for the Baltimore chapter of the International Game Developers Association.

"You look at any other type of media and people have the freedom to press the boundaries," he said.

In addition to constitutional concerns, the video game industry has been worried about how potential restrictions could affect game sales and growth, which have been on an upward trajectory in recent years.

Bethesda Softworks LLC, a Rockville-based game developer, can take several years to create a game and unveil it to a worldwide audience. Pete Hines, spokesman for the company, said it has been making "brutal, post-apocalyptic games set in an alternative universe" — with great success.

Two of its games, Fallout 3 and Fallout New Vegas, have each garnered more than $300 million in worldwide sales, he said.

"It's always been our stance that there's a mature audience we're making these games for," Hines said. "We feel like there's an audience for those games, just like there's an audience for slasher movies."

The appetite for video games in general keeps growing.

In 2009, worldwide video game sales were estimated at about $60 billion. They were projected to grow to $70 billion by 2015, according to DFC Intelligence, a market research firm.

In Maryland, video game companies, many of which are based in Baltimore and Montgomery counties, are part of a digital media industry that in 2008 reported $5.5 billion in sales and employed 32,000 people, according to a state report released last year.

New markets in gaming online and on mobile devices are driving growth in the video game industry beyond just computer and console games. Video games on Facebook and the iPhone represent two new, vast markets.