OK, this is going to sound a bit… sociopathic. Or perhaps psychopathic. In any event, it's something that I'd only do playing a game — I swear! :)
I will soon finish Point Lookout for the second time. It's the last bit of DLC for Fallout 3 in this, my fourth run-through of the game. I will have accomplished most of my goals (having gotten all but 20 of the unique weapons and articles of clothing). After I finish Point Lookout, I'm going to be a bit on the "bored" side in terms of X-Box gaming until New Vegas comes out.
So until then, I was considering going on a personal challenge to obliterate all of man- (and ghoul-) kind in the Capital Wasteland. I know that random encounters will still pop up, but I was figuring on going to every town, every settlement, every everywhere, and wholesale slaughtering everyone I came across.
Aside from the obvious ramifications — shops no longer being available, so no trading to be done — what are the ramifications of making a "last man in the world" (well, at least the east coast of the US) situation in Fallout 3?
Update:
If you're gonna do it, have fun with it! Pint-Sized Slasher Mask and children's Blast-Off Pyjamas FTW.