There is a city called Nexus, at the Crossroads of All Worlds. On every world, there is a portal to Nexus, and from Nexus one can travel to any other world. In Nexus, all technology, all magick works. However, the portal removes all weapons, and within the City no offensive magick works, except for the elite members of the Ruling Family and their Praetorian Guard. Given the ease of travel, though, this restriction means that Nexus is a very desireable city, and the small tolls they charge for entering make it exceedingly wealthy indeed.
The City itself has become a haven, of sorts, for all sorts of expensive and illicit pleasures, of every kind and description. The most glittering jewel of all of the city, the most opulent and magnificent pleasure palace, is the Chalice of Joy. It is a huge complex, almost a city in itself. There are shops within for buying all sorts of luxury items. There are dens where the drugs, both legal and illegal, of a million worlds are sold. There are casinos, and fantastic restaurants. There are guest rooms, where those partaking in the pleasures here stay. But first and foremost, the Chalice is a brothel. The *best* brothel, with the best workers, in all the known worlds. It is fabulously expensive to patronize the Chalice, and workers here can make a lifetime's pay in a single year. But few reckon the cost to the workers themselves of that year...
The Goddess of the Chalice is known as the Steel Angel. Humanoid but not human, no one knows her past. But she has run the Chalice ever since it opened a thousand years ago.
The idea is to have a game with yeah, sex, but to explore the whole idea of what mentally and emotionally and spiritually these people would experience. Also there will be intrigues and plots and interactions with the other parts of the Chalice. For those who don't want to play sex workers, they could play people in Security, people involved with the drug dens, or some such.