Firstly, to the OP: I had a bad experience once where I stubbornly refused to use a safe word during sex. That brief window of time where I was utterly helpless and unable to stop what was going on gave me a tiny little window into what it might be like to be raped. So, from that meager perspective that in no way compares to yours (I like to think it makes my sympathy stronger), I hope you continue to improve in whatever way constitutes improvement, and I appreciate you stepping out and giving me better understanding into traumatic experiences.
That said, I feel like the people who are arguing one way or another just don't get it either way, or are so wrapped up with proving the other side "wrong" that they are refusing to truly consider things.
I'll tell you guys a story. In high school I was in the drama club. One day after school myself and two of my friends were sitting on the stage making awful jokes about just about everything. We got around to epilepsy, and before we knew it a teacher marched into the theater and told us to get our butts to her classroom. Unbeknownst to us her daughter had been listening to us in the back of the theater. We didn't know her very well, but guess what? Yup, she had epilepsy.
It didn't bother me that the teacher wanted to punish us, because yes we were being inappropriate and crass and saying things in school that you aren't allowed to. What bothered me was that the only thing she wanted to punish us for was our comments (and er. . .caricatures) of epilepsy. We had no way of knowing that her daughter had epilepsy, or even that she was watching us. Yet the teacher, blinded by her own motherly instinct to protect her daughter from hurt, inadvertantly gave us the message that all the other crude comments we were making were okay, but epilepsy was one holy subject that should never be made light of.
Here is my thing: if you are going to be sympathetic or empathetic, be that way about everything, and understand the venues. With close friends, I can be crass and rude. The second I see something is up (the way they talk, body language, etc) I stop. I won't press into it, but I can see that something is wrong and so I change the subject.
With strangers, I do my damndest to avoid the most common controversial things in order to not hurt a stranger, unless the venue calls for it (a discussion about it or whatever). Do I slip up? Of course, I'm human. But the point is, I have enough respect and concern for my fellow humans to put in the effort. Do I still use some words that could be considered hurtful? Yes. I use 'retarded' pretty frequently. Would I stop using it in the presence of someone who might find it hurtful? Absolutely.
Now, the difference between some of these words is the amount of personal involvement. The word 'genocide' is nothing more than a sort of statistic to most of us who have the luxury of playing video games, so it's less likely to have people defending it. Is it awful? Yes. Are you going to cause someone emotional or psychological pain/suffering by using it? Probably not. Does that make it okay to use in a casual, offhand manner as though people dying horribly is okay? No.
But in a lot of ways we are still children when it comes to horrible acts. Rape is a little more understandable, because for most of us we have had some sort of emotional hurt and have the brainpower to realize just how much more painful that would be over something that didn't wreck you. Sometimes in our inability to understand something we tend to make light of it because it is strange and foreign to us and that's what we tend to do. To me, that's in some way normal. However, even if you don't understand why something might be especially painful to someone, the polite thing -- the thing that imo makes humanity worth something -- is to try to act in a way that will no longer cause that person distress.
And the argument here inevitably becomes one of morals. If you are not in a headspace to care about other people, then you aren't. I've met some people like that, over the years. They are not people I care to be around. But, it is not my place to condemn them. In my mind, there's no telling what happened to them to make them that way, and in more cases than not it's something I pity them for. However, will that stop me from trying to ask them to behave differently so as to not cause harm (even if it seems stupid to them)? Nope.
Now, with all of that said, rape in my mind deserves a little more solemnity than words like 'murder' or 'genocide' in most first world cultures when dealing with your fellows simply due to the fact that you're far more likely to run into someone whose life has totally been screwed due to it. It's really damn unlikely you're going to cause pain to someone who experienced the trauma of seeing a close one murdered (as to me that's the only way the word is comparable to rape within the context of the discussion) or genocide. Does that mean I think people should go about using any of those words as though they are not each terrible things? No. But it does mean that I think using the word 'rape' indiscriminately as some sort of power word, while being cognizant of and understanding the pain it causes others, to show your domination over someone else is immature as all get out and a sign of someone who does not, in the end, care much for his or her fellows and not someone I would ever want to have anything to do with.
Also, as someone else said, saying 'I murdered you' in a video game is usually demonstrative of what is actually going on in the video game. Now if we want to talk about how murder/killing in video games is harmful or whatever, I think a new thread is needed for that.
Aaaand that's my soapbox for the year.
edit - one quick thing: saying 'I want to murder your mother' or 'I want to commit genocide upon you and your people' is as offensive as lightly using the word 'rape,' in my mind.