Currently the game industry regulates itself through the ESRB Rating system. This is what you see on game boxes, the "E for Everyone, T for Teen, M for Mature" etc. The video game industry is self regulated, much like the MPAA for Movie Ratings. Industries do this to AVOID having Government regulation because it's a huge pain in the a$$. Right now game developers, publishers, and everyone in between are watching this because they don't want to have any more red tape or regulations that would ultimately affect sales and revenue.
I'm for regulation of violent video games, violent movies/music, etc, but let the industries regulate themselves. It's worked fine so far; How does the saying go? If it's not broken, don't fix it?