What sort of video games are ruining childrens lives

I would say it's less the game, and more of the community that has it's impact on children.
Video Games aren't necessarily ruining childrens' lives. It's more of the parents' fault than a video game if a life is ruin because if a video game has more influence over a child than their parent does...well that's self explanatory.
Children should only be introduced to video games the parent feels their child is mature enough to play. I've met 9 year olds playing M rated games that are completely mature, and even more mature than most teens that play M rated games. It's more about maturity than it is about age. Just because someone is 17 doesn't necessarily mean they are mature. It's sad, but true.