Here's my theory about that incident. The late perp had no agenda other than he lost and was pissed off. No causes to promote, no women to get back at. Just the rage at failing at something that he was normally good at. Video games didn't cause this anymore than playing cards caused people to shoot each over poker in the Wild West. Nobody likes losing but some people just don't handle it very well. Most of us are happy with being allowed to graduate with a B average, and yet some are devastated when they get an A-.
Raw emotions caused the Madden shooting. The perp had raged quit on life itself. For a moment, let's set aside the debate on gun control. If your emotional control is so weak that you'll throw a $60 controller at a $200 TV set, you shouldn't have a gun. You risk doing something you'll immediately regret for the rest of you life.