IC: Fallout (probably Adult, probably GURPS)
Adult primarily for violence, horror, the use of chems, and for attracting players who are mature enough to handle these elements. Anything erotic would be incidental and in the background, with group access for only the players interested in seeing it. I'm all about the story as a whole, and for me that includes allowing the things that people would otherwise "look away" from.
That said, if interested players are primarily set on a Mature setting I can do that instead.
New Orleans would actually be great for this story, utilizing a streetcar to get around town for trade.