Take an ambitious young, possibly even a bit arrogant, heroine
(what can a man do when young?) with some interesting sexual kinks.
Give her a patient and wise mentor, who is not void of his own
personal problems, inclinations and passions. Spice it up with a
pound of promiscuity, add a half-pint of humor. And finally place
it to simmer on the low heat in the city full of supernatural
mysteries, in the city braided with web of intrigue, sunk in vice,
riddled with corruption and smog bound. That's how you create a
quality novella-game for adults.