Just looking at my shelf of games and my collection on Steam, a disturbing number of titles that I have played simulate violent acts. There are entire genres of games called shooters. In strategy games, by and large, one strategizes in order to kill one's enemies. Role playing games tend to focus on combat. Even sandbox or open world games seem to offer open worlds where one can kill and destroy on a whim.
One very popular way that games makes violent acts seem acceptible is to frame their action in settings that reasonable people would agree justify violence. This can be done with varying degrees of success and requiring varying degrees of willful suspension of disbelief. Let's call this way of justifying violence the Just War Doctrine.
Using one of 2007's top shooters: Call of Duty 4. The Call of Duty series has had a lot of success simulating World War II (the good war). One would have a difficult time arguing that the old chestnut of killing Nazis isn't justified by the crimes against humanity committed by the Third Reich. Not only is the player justified by simulating a soldier for a nation at war, but they are additionally justified by fighting against the perpetrators of the holocaust. The 4th installment in this series moves the setting from WWII to modern warfare. The player still has a cloak of justification given by wearing the uniform of a country. (Players switch back and forth between playing a British S.A.S. soldier and a member of the U.S.M.C.) Why is it ok to play a game where the object is to shoot and kill one's enemies? It is ok because the violence has been sanctioned by a democratic government.
To the credit of Infinity Ward, the creators of the Call of Duty games, they do raise ambiguous and troubling questions. In one memorable mission, I played an S.A.S. soldier raiding a freighter at sea carrying a rogue nuclear weapon. When the announcement comes over the radio "weapons free. Crew, expendable" My squad opened fire on the unsuspecting and unaware mechant sailors navigating the boat. The emotional impact of this was very different than fighting the so-called terrorists on the ship who were armed and opened fire on us.
Deliberately simulating violence that is less easy to justify than fighting against the Nazis doesn't mean that COD4 leaves the just war doctrine behind. Successfully completing that mission saves the world from a nuclear device in the hands of extremists willing to use it against civillians. The cost may be high, but in the end the balance sheet shows the violence as justified.
Many other games don't come anywere near the line between justified and unjustified violence. Whether the enemy are ravenous orcs, hordes of zombies, xenophobic aliens, or demons from hell, game designers go to great lengths to de-humanize the violence by having the players fill the role of humanity's last hero fighting unhuman evil bent on destroying all of us. After all, what is the ethical response to an undead invasion bent on eating humanity's brains? Load your shotgun and grab your crow-bar!
Some may make the valid observation that simulating even justified violence has a negative effect on the player. This point is well taken, even though some studies show that children who game are at least as well adjusted as children who do not. Looking at the games themselves, many at least put a veneer of justification on violence and simulated carnage by creatively finding situations that many reasonable people would say justifies violence.
Next up: games that don't offer a justification for violence, but ask the player to simulate the context of people driven to violence by their situations. We may not be able to say these actions are good, but we may come to understand how people can find themselves doing horrific acts.