I may have been a bit reductive. There are certainly games out there that stress positive acheivement. However, there are far more that depend on the player committing several acts of violence to excel in the game. My comments certainly do not apply to all games but I think it describes a pervasive and widespread trend in gaming. You must kill to win. We may choose to fight for the Allies or the survival of the Jedi or to save the Princess, but the fact is violence in video games is a very common component and gamers demand it. Lets just consider a few titles:
1. Half-Life
2. Halo
3. Call of Duty
4. Mortal Combat
5. Total War
6. KOTOR
7. Doom
8. Mario Brothers (Even Mario must kill)
9. Pac Man (I wonder if consuming ghosts causes gas?)
10. Battlefield
11. WoW
12. Zelda
13. Madden
14. etc., etc., etc.
Even the seemingly benign Nintendo staples depend on violence. It may be cartoonish, but its still violence and death. If you prick a Koopa Troopa, does it not bleed?
![Frown :( :(](data:image/gif;base64,R0lGODlhAQABAIAAAAAAAP///yH5BAEAAAAALAAAAAABAAEAAAIBRAA7)
Super Mario Brothers is somewhat disturbing, because the guy goes through this 8-level killing spree with a big huge grin on his face to mostly happy-go-lucky music. If you think about it, its a little creepy. That Mario is one twisted puppy if you ask me.
Sex in video games is a whole other issue. In our culture, its more acceptable to let teenagers watch violence, murder, and bloodshed, then nudity and sex. Just think Hot Coffee. You can kill a hooker for the trick money see just got from you, but god forbid if you show the actual act of sex. However, If they did allow sex in MA games, Hot Coffee and scenes like it would be everywhere.