It depends on the games the kid is playing and it also depends on the kid. There are wholesome games and there are edgy games. There are also good kids and bad kids.
The kids who you need to be worried about are the kids who love games like Grand Theft Auto or Saint's Row where you're expected to be the bad guy, who also see the greatest form of heroism as "standing up for yourself and not taking anyone else's abuse/unfairness/mistreatment." Abuse, unfairness, and mistreatment are very abstract and arbitrary terms. The younger you are, the more likely you are to see abuse, unfairness, and mistreatment where none exists. And if you're one of those people who doesn't take what you see as abuse or mistreatment or unfairness from anyone and believes everyone is out to get you, that's a huge problem. If you destroy everyone who's unfair to you, then you'll end up all alone. And if everyone destroys everyone who's unfair to them, there won't be anyone left.
A lot of kids don't understand what maturity is. Or worse, they understand what maturity is but don't want it because they see it as a liability instead of an asset. They equate maturity with being a chicken, a chump, a doormat, a pushover, a wimp, or a wussy. What we need to help kids understand is that a lot of the people they see as chickens, chumps, doormats, pushovers, wimps and wussies go on to do really amazing things, and that a lot of the people they see as heroes are either the most likely to end up in the emergency room or in jail, or the first to end up in caskets.