Here's the thing.
Video game violence means nothing, and playing video games means nothing when you are young.
However, this is only assuming the following:
1. Reasonably mature kid
2. Reasonably mature parents. By that I mean, the reason why violent video games are bad for some kids has nothing to do with the fact that it's because there is gore and it will "kill their innocense", but it has everything to do with the parents simply being bad parents, who try to shelter too much or don't raise their own child (in the sense that they never teach them anything, don't give them a sense of identity or responsbility, etc). Mix violent video games with that, and you might end up with a problem child as a teenager. He'll, mix any medium with that and thats what will happen.
I played relatively violent games as a kid but it was never something I did all the time (I kind of had limited access, but my dad would sneak me in some time when mom wasn't looking

). I'm 21 now and I'm pretty sure I'm more mature finaically, socially and mentally mature than most other advlts my age. I pay my own schooling, bills, etc from my part time job while also going to school full time. I treat people well, and hate taking advantage of people.
Really video games have nothing to do with it. It's the parenting that has everything to do with it, and what kind of personality type your kid is. Hopefully if you are a good parent, you'll know what personality type your kid is, and be able to not only respect it but also know it's limits, if it has any you should be concerned about. And as such you'll be able to make good choices when it comes to things like this.