I do things I normally wouldn't do in real life. I do not, however, as a self preservationist, burn bridges, and I do compromise when it suits my agenda. I don't really give a damn about which side is the correct one, as far as I am concerned, the only correct side is mine.
Sometimes, though, i just do bad things because I feel like it. I typically align as a neutral chaotic.

I see it as a http://en.wikipedia.org/wiki/Catharsis phenomenon. I do things I would never do in real life just because I can without consequences. When I get frustrated for whatever reasons, I sometimes go on a killing spree, quit the game and maybe reload. But most of the time, that's because I need a break.
I like stealing in games but I would never ever tarnish my name like that IRL. I much prefer play games than watch real life gladiators fight to the death.

I play games to kill time and socialize with people. Games have never been an effective stress reliever for me, nor have they been a way to express myself.

In games like GTA, I tend to kill anything and anyone... that's the way to play.
But in games like TES and Fallout, I usually play as myself, a nice, chill guy. c:

It depends on my mood and what character persona that I have in mind that I'm playing. I usually play as what some might consider to be lawful neutral characters but other times not so much.

I have never been into mass killing in games for they often bore me with the exception of ACFA where in one mission arc you could kill 100 million people and found myself gigging. Instead however I sometimes take a much greater delight when I can turn people against each other or general schemes of manipulation (one example being in KOTOR where you can get 2 feuding families to kill each other). I see this as letting loose the inner id for what I would consider to be an theraqeutic exercise. Mind you however I don't do this for the sake of stress relief or letting lose anger on some pixies but rather for working out fantasies for personal amusemant mostly.

I like playing different variations of character.. but I'm still me

Most of your killing? Oh my...