It's funny, I was actually contemplating today how the artificial lives we snuff out could very well be no different than our own. Seeing as we may be living within a computer program ourselves, we're essentially just snuffing out less advanced lifeforms of our creation.
It's more like shooting your television, or google translate. Try playing Master of Orion II and notice that the AI cannot adapt or learn at all - it can only do things that it has been programmed to do, and will never do anything intelligent or surprising once you understand it. You can hit it again and again with the same strategy that it fails to handle, and it will
never adapt. And that's the AI for the emperor of a nation, to say nothing for the population on planets, which has no AI at all and is just used as numbers in calculations.
No game AI is Strong AI as far as I'm aware. If there was, then there'd be a moral concern, but there is no Strong AI in existence in the world. Some game AI seems to adapt, though (Sword of the Stars AIs appear to develop techs and ships to counter yours, but this can easily be coded in algorithms and doesn't require intelligence). Even programs that use neural nets today don't even have the intelligence of a real-life fly or mouse - things which you would likely not think twice about killing simply because they're nuisances to you.
Now while games like Aurora 4X have people as a simple spreadsheet number, we also look at numbers of people in real life the same way. Look at an AAR of a real battle and you'll see the dead, injured, and missing as a simple number on the screen. That's all they are to most of us.
Some numbers may be abstracted people, but that doesn't mean all numbers are abstracted people.
I've recently begun to show mercy in games (except my recent CKII playthrough, don't look into the last couple pages of that topic) as a result of my recently evolving views on artificial intelligences, though I do have to actively think about it or else it's explosions and slaughter as usual.
Anyway, I'd say on a scale of zero to everyone, I've killed a few googles of folks.
It's a fine thing to consider how moral your actions would be if the game you were playing was real, and part of roleplaying, but you're anthropomorphizing numbers, algorithms, and art designed to give an illusion of humanity, one which is easily seen to be illusory if you test it or think about it at all. (For example, in Half Life 2, shoot Judith Mossman in the elevator while she's speaking. She is unharmed, doesn't stop speaking, and
doesn't even notice, because she wasn't programmed to react in any way to attacks and they can't harm her.)