LOL. I have played so many games. I am often pretty ethical within the game’s context. But I’ve played games where in some modes involve acts that go beyond war crimes
e.g.
Dominions, where you can lead a nation run by vampires, dark gods, Cthuloid gods, the undead (where you’re trying to kill off your own population and pretty much every living thing) or users of blood magic (where you gather virgin sacrifices to use in spells that do even more horrible things).
I’ve played Carmageddon, where you get points for running down pedestrians and animals, and bonus points for doing it in creative or especially horrible ways.
Oh, and Evil Genius, where you get extra rewards for devising a particularly fiendish and diabolical demise for the heroic agents investigating your lair.
Even when I’m being ethical, sometimes I’ve done some pretty cruel things, like put the gimpy soldiers in the front to act as scouts and draw fire, since they’re not very effective, may have trouble reaching the front if they were in the rear, and if they get re-injured or killed, it doesn’t take out a fresh soldier, and means I have less wounded to take care of… though I wouldn’t do that if/when the games in question give me more humane and sensible options.
Oh, and this reminds me. Once I was feeling pretty angry about a Fluther question where someone was talking about their crappy parents’ righteous abusive behavior towards them, and I decided to work it out by playing some Grand Theft Auto. I went around looking for a big vehicle to carjack and go on a rampage with, and found a large ice cream truck with a two-man crew. I pulled the driver out of the truck, and his friend came out to help, but I dodged a punch by one that hit the other one, and they started fighting each other in the middle of the street. I took their truck while they were fighting, and ran them both over with it, and proceeded to go on a rampage, but it quickly wore out my anger and had me noticing it was taking more and more effort to imagine the victims were bad parents. Um, but then before I quit, I found an armored car and was able to steal it and go on a rampage with it, which was practically unstoppable by the police, until I foolishly rammed a concrete barricade and got stuck. Of course being GTA, they just arrest you, fine you, take your weapons, and release you.