Eric Davis and Dylan Klebold, the two students who killed 13 people in Colorado, enjoyed violent movies and video games.
Games like Quake and Doom are called "twitch" games, and are popular among teenagers.
In its defense, the game industry says only 30 percent of its games are violent, and there may be less violence soon.
"I think what you're going to see is less violence in video games because I think right now you're seeing a huge backlash towards it," says Michael Backes, a movie and game writer.
At the Electronic and Entertainment Expo in California, almost 2,000 new games will be introduced. Game makers defend themselves by pointing out that their products have been rated on violence and general content for a couple of years.
"If consumers pay attention to the ratings on the box, and take the time to inform themselves about the products their kids are involved with, and also the activities their friends are doing, I think that's really the way to go," says Wes Nihei, a game magazine editor.
Critics say the warnings are too small and too vague. Gaming insiders say more powerful computers may help reduce the need for twitch.
"A lot of the violence and kinds of action elements in video games today are due to the limitations of technology in the past," Backes said.
Games such as Myst are growing in popularity as the age of game players increases; older players enjoy more thinking, less blood.
"You're starting to see games that have really more content to them and less twitch," Backes said.
Unless game makers move away from violence on their own, pressure from lawmakers could force the issue.
Computer and video gaming revenues have grown quickly and almost match revenues from the movie industry.