Warning: long, geeky post ahead. Also contains mild spoilers for the Call of Duty games.
Slavoj Zizek has a penchant for military PC games, as he noted in a Guardian piece when asked about guilty pleasures back in 2007. (The Roger Scruton entry is an oddly charming bit of self-parody, by the way.)
I play them compulsively, enjoying the freedom to dwell in the virtual space where I can do with impunity all the horrible things I was always dreaming of - killing innocent civilians, burning churches and houses, betraying allies... Plato was right: there are only two kinds of people on this earth, those who dream about doing horrible things and those who actually do them.
What's odd about this is that there's very few, if any, military PC games in which it's possible to commit atrocities. The digital battlefield is one scoured of civilians. I am a total Company of Heroes addict, and have occasionally dreamt of a grimly Fussellian mod in which, for instance, one's mortaring of a house containing Wehrmacht troops is also likely to kill the French family hiding next door. Company of Heroes does sometimes produce friendly fire moments, but not with anything like the frequency they occur in real warfare.
Naturally, the impulse if it *was* included would be to pull off the most spectacular digital atrocities, because it's fun. I can still remember the magic of setting people on fire in Syndicate back in the day; at one point my friend Matt was employed at a Canadian games company to make the fire effects more realistic in a game entirely because so many people loved burning their opponents.
This applies only to modern games, I notice. In the Total War series, massacring civilians, hiking tax levels to a point where the peasants rise up, and executing one's prisoners is all part of gameplay. (Unfortunately, they got rid of the ability to kill prisoners on the battlefield a la Agincourt between Medieval: Total War I and II; it made a very satisflying "schlick" sound when you pushed that button.)
On the FPS side, I haven't got around to playing Black Ops yet, but I gather it has, at least in passing, a civilian element. Call of Duty : Modern Warfare 2 had a "controversial" level in which you had to play a CIA spy participating in - or at least failing to stop - the massacre of civilians at a Russian airport.
But it wasn't very good exactly because it was a *hard men must do hard things* narrative - c.f. the frequent approval of torture a la 24 in the franchise - and the presence of civilians elsewhere was desultory - there's a brief bit where you're penalized if you accidentally kill them, though I believe you're allowed a kill quote of three. By accident, of course. It was, however, pleasing that the CIA operation turns out to be an utter, pointless failure, probably the most realistic element of the game.
The Call of Duty franchise has got less interesting as a whole as it goes on. Modern Warfare 2 has the ridiculous Russian invasion of the US - where there are no civilians for the killing, nor even any civilian bodies on the streets, unlike the Russian or South American set levels. This is a shame, because it ruins the most interesting part of Modern Warfare 1, which very neatly conveyed the realities of overwhelming US military force, mostly through its shifting viewpoints.
There's a part where you go from shooting on the ground to being the gunner on an attack helicopter, which is done in a detached, dots-on-the-screen fashion that's chilling - and uses the staccato jargon of the real military instead of the overwrought drama elsewhere. Some designer should go the logical route and make a game where you play insurgents facing the US military, sneaking around, watching air power devastate your neighborhood, and planting IEDS, but given the flak that the latest Medal of Honor took for just letting you play the Taliban in multi-player, this seems unlikely. (It would have been a much more interesting way to do the Russian invasion plot in MW2 to have the Americans effectively acting like insurgents elsewhere.)
I liked the original Call of Duty games (and Medal of Honor: Allied Assault) because - well, because shooting people is fun, especially when they're Nazis. Any game where you can kill Nazis* is good by me. But also because the first two games in the series (4 is distinctly inferior for all kinds of reasons) had great moments where they forced you into being a passive participant. The fundamental experience of war is to have things done to you. (Elaine Showalter talks about passivity and feminization very well in Hystories.)
Passivity is obviously even more anathema in computer games than it is in most movies, but the Stalingrad scene in Call of Duty, where the guy in front of you gets the gun and you get the bullets, and the Omaha beach scene in Medal of Honor do it fantastically, because suddenly you're no longer shooting people - you're just failing, again and again, not to die. Until you figure out the machine gun pattern, that is. Then you're sorted.
*Or 18-year-old conscripts, if one thinks about it too hard. But I do love the bit with the Russian gunner on the roof. "This is for my mother, you bastards! This is for my father! This is for my sister! And this ... is for my dog!"