over 250 billion (99.33% due to Star Wars Rogue Squadron)
Remember that Mission in Star Wars Rogue Squadron where you blow up the Death star? Yeah I've done that 100+ times, my favourite level.
There has to be ATLEAST 2 billion people on that Death Star, and I blew up the damn thing many a time.
Then I've killed atleast 17 million zombies in L4D1, and about 7.5 million zombies in L4D2...
Then I've killed alot in flash games.
Then there's all of those RTS's I play, that usually end with 60 thousand dead per person. (And I've played alot of those)
Then I know as a FACT that in cod4 I have over 500 thousand kills online, then include all of the bots I've killed in single player, that makes cod4 = about 1.5 million
Then there's all of the other shooters, from which I can put down an easy 25 million.
Then about 700 people in Sims...
Then count all of the grinding in RPG's that's gotta be over 5 million.
*Edit, add in