He is 8. It is your job to be mean and to protect him from himself. I DO know how hard that it. At school, do the adults know they are acting out things from world of warcraft, etc...? Here I would tell the teacher and the office mgr and they would make sure that the recess monitors did not allow it. If the kids persisted they would be forced to not play together because that just isn't an appropriate thing to do. I know we all played cops and robbers and whatever but it really sounds like they are just focused on the violence and need to be more closely monitored.
We had a LOT of problems with violence and Wiz. I did some things that poeple here didn't agree with all the time but now Wiz has thanked me and said he hated me for doing them but he needed them. I always had a big problem iwth anything that my kids would lie, cheat and steal for. If you "need" it so bad you will lie, cheat and steal to get it, then as a parent my job is to cut that influence out of your life. That meant I put away ALL videos of any kind with any kind of violence. Disney videos are AWFUL for kids who perseverate on violence. There are LOTS of dramatic violent scenes in these "kid" movies. The hyenas taking a dramatic pause and then yelling "We'll KILL you!", The fight in Beauty and the Beast wehre the villagers are after Beast, all sorts of thing. We didn't have cable or any pay tv service for this very reason. I wanted to control what the kids saw when they were little. We spent that money on videos because videos have no commercials and you have total control over them. I would pack them up and store the ones that were triggering Wiz' need for violence in a storage unit so Wiz coulnd't break a door down and find them and couldn't sneak them.
MANY people told me this was the wrong approach. My gut didn't agree. Some of the psychiatrists agreed with me, some didn't, most wanted me to let Wiz earn time watching these. NOt in MY house. If they wanted to live with a child who wandered around the house looking at every single thing to see how he could use it to hurt someone, they were welcome to. Because that is where Wiz went when he had too much access to violent video/tv/computer stuff.
Your son is eight, right? You said you were blocking things above pg13. Why is that? Do you honestly believe that the pg13 images have a level of violence that is good for him to see? Forget what he enjoys. Is this healthy for his developing and perseverating mind? Does he need the idea that at 8 it is okay to have stuff rated for 13yos? Our kids want things way before they are ready, and I don't always agree wtih the ratings about whether something is okay for my child before that age. It is our job to reisist their demands/whining and to evaluate if this is really right for them. It is HARD and they call us all sorts of names. have the benefit of my own "you tried to force me to do X so there is NO WAY that X is going to EVER happen" atitude - I truly HATE to be pushed to do anything. Usually it isn't an issue, but if someone tells me I "have" to love something, or pushes me to watch something because everyone does it, my brain automatically goes to I WILL NOT NOT NTO NOT NOT. even as a kid I could control this and was NOT oppositional, but when Wiz would start telling me I "had" to let him do this or watch that, and got tdocs to AGREE that he should watch R rated movies before he was even 10, it was useful to have that side of my personality. One idjit therapist wanted us to let Wiz earn time playing some online rpg by not hitting anyone. Every hour he didn't hit someone he earned x amt of time to play this game. He was 7. He was NOT playing some online game. The game was rated for adults, not teens. It was NOT happening. Even if it hadn't been online, it wouldn't be played by my kid. The idjit therapist could not grasp why I wouldn't allow it. I couldn't understand why he was so stupid (the therapist) because every single note in Wiz' chart mentioned how he acted out whatever he saw on tv or computer games and how he did not understand the difference between fantasy and reality at that time.
That was us, and my oppositional brain kicking in. YOU have to figure out if these games/videos will enrich your child's life to a degree that is worth encouraging his perseveration on violence. None of us can answer for you.
I used to take away ALL electronic screens from the kids sometimes. Usually when Wiz would lie cheat and steal to get to watch something. The first week or ten days was pure Hades and then something magic happened. They started using their creativity and became delightful, fascinating amazing people. Yes, even difficult child. Of course it was harder for us because they were into everything and not brain-dead staring at a little screen, but it was worth it to me. The good behavior earned back the electronics and we tried to keep a middle ground but it was hard. We did this maybe 1-2 times a year.
That is how I handled things when the violence took over Wiz' entire life. I used the guideline of "lie, cheat, steal" to help ME keep the boundary clear. ANY item my child would lie, cheat and/or steal to get had to be removed from our llives as much as possible. I found a MUCH nicer, more fun, less oppositional kid was under there when I cut out the media or at least limited it to Winnie the Pooh/Barney types of things and cut out all the violence. I do know this won't work for everyone.