At my age I don't play video games but sometimes I wonder if some of todays generation have problems separating games from the real world. Maybe like dropping a shopping cart from four floors up, critically hurting a woman, and laughing about it.
As far as the real thing, I was not in combat but served in a medical company in Korea during the conflict.. Real life combat and the resulting injuries and deaths are NOTHING, NOTHING like a game!

Ask RJ, a five time Purple Heart recipient.
I used to poo-poo the idea that video games caused delinquency in young people, but I've changed that opinion. I don't necessarily think that a normal, well adjusted kid playing Vice City (one of my all time favorite games BTW) is going to turn into a homicidal maniac, but take a kid who's already got issues and add something that simulates mayhem and makes in downright enjoyable and well, I can see that having a negative effect. That's why I personally have no problem with game ratings and I think parents need to be more careful about what games their kids play. But I do NOT believe in any form of government censorship.
And while the simulated combat in games today aren't truly "realistic" I would think they'd trigger more episodes of PTSD than they do. But combat vets are made of tougher stuff than most of us think yet, are very fragile in certain ways you might not expect. My FIL was in Nam in the Thundering 3rd and saw a lot of action. He loves war movies but he's deeply unnerved by the dark. That's not inconsistent with a lot of other guys I know. My other bud who served in the 10th Mountain in Iraq as a UH60 crew chief has no problem watching war footage but certain smells really bother him because they remind of particular events.