Having nieces & nephews in my family who play "Halo," I know, from watching them, that the involvement in this game can be intense. However, having said that, there is more to this story than the media is reporting (perhaps blocked by the Judge, prosecutor, in this case?)
Having a father who is a minister, having a mother, and having a handgun locked-up, the Ohio teen got the key, unlocked the box with the gun, took the gun & shot his mother & father, and left with the game in-hand. This shows "intent" & "premedatation." In other words: there was something "more" going on within this house, & this family, than was reported in this news article by the news media. Male teens get angry, upset & intense. They don't have complete brains yet; when they feel something, they feel it compeltely & intensely. Emotions escalate, quickly. I believe the parents tried.