The problem is, we're blaming video games because we think it takes the heat off guns. Yet, it's the same knee-jerk reaction the gun-grabbers used in the days following Sandy Hook. We don't want our guns taken away, so, oh, the shooter played video games? Must be it! The one commonality we have with nearly all mass murderers is they have some type of mental issue. But there is no such correlation between video games and mass murders. Many mass murders happened prior to video games. Some recent mass murderers didn't play video games. Most people don't realize that the VT shooter did NOT play violent video games
(even though right afterwards, there was a huge knee-jerk reaction blaming them!
About the only correlation that can found between violence and video games is that they can influence the "type" of violence, and how it's perpetrated. But studies that have been done seem to show that violent types are attracted to violent video games. They are used by people who are already violent. They don't cause violence. In other words, if you aren't violent, and you play a violent video game, you won't become violent. If you're already violent, and play a violent video game, it might change how you manifest your violence, but it won't make you more violent.