There are basically two things you can’t do in a videogames here.

1. Sexual Violence - it’s just not allowed, the South Park scene falls here.

2. Realistic and/or beneficial depictions of drug use - This is where Morphine to Med-X falls.

Violence hasn’t been an issue an ~15 years, but used to be an issue since we didn’t have an R18 rating for games, they topped out at MA15+, so violence had to top out at what was acceptable for a 15 year old and no more, but that’s a thing of the past.