This is an old game series, but it was proof that you could put as much blood and gore into a game as you wanted and still get a Teen rating in the US, as long as you're just killing/dismembering Nazis.

BloodRayne. There's a "cheat" to change a few of the visual effects. One makes her put all her weapons where she is actually storing them, and shows the unused weapons at all times. One makes the blood spray levels "more accurate to the actual amount of blood in the human body. The last one just makes her boobs bouncier.