The game kicks off with John Constantine receiving a message in 2013 from 20 years in the future from Rip Hunter, who tells Constantine that cataclysmic events have left all of the world's governments and most of society in a state of collapse. Naturally, people turn to superheroes for guidance and leadership—but years of this new order have left many of the heroes into a power hungry and politically motivated Noble class with mortal men and women as peasants.
The heroes have divided into Houses, with Superman and his now-wife Wonder Woman leading the House of Steel and controlling most of North America and sections of South America, while Captain Marvel and family have established their own domain out of Europe as the House of Thunder. There's also a House of Titans (former Teen Titans), a House of Justice (ex-Justice League members) and so on, but Steel and Thunder are the most powerful.
The remaining supervillains have likewise established their own Houses, most notable among them led by the Joker, the House of Laughs, and Lex Luthor, the House of Secrets after a worldwide purge of villains following the degradation of world governments. Batman leads the non-powered heroes in an effort to overthrow the two dominant Houses. All aliens, including the Green Lanterns, have been banished. But everyone soon gets involved in a plot to destroy the Houses of Thunder and Steel before a wedding between between their Houses unites them into potentially the most powerful force in the universe.
Play as an entire superpowered House, a single hero sent to the future to aid Batman and his group, or a wild card with your own agenda. (Deathstroke anyone?)
Given enough interest I'll put out a CS template and roster. The smut factor in the game is really subject to each player and/or faction, and how they establish their own unique ways of doing things. The plot and setting are pretty well thought out already, but if you know your comics and have input about possible additions/changes, PM me! I'm always open to good ideas and changing the game for the better.