It was a "Madden NFL" video game tournament. It's a football game, not a shooting game.
That aside, I'm not surprised there would be a shooting at a video game tournament. Not because "video games make people violent", but because "gamer culture" includes some of the most bitter and entitled social rejects on the internet.
-k
Sounds like this so called "gamer culture" got this guy violent...also dead. Maybe that's why I've always found it so repulsive.