Since the great majority of North American retailers flatly refuse to sell 'AO'-rated games (regardless of actual content), initial distribution of Singles in the U.S.
Because the game features full nudity and portrayals of sexual relationships, it has been rated 'AO' ('Adults Only') by the ESRB. Properly wooed singles will eventually undress in front of one another (and the player) as they become more intimate.
Singles was designed for the European market, where many Americans might find the general attitude toward sexual expression to be more relaxed. Unlike in the Sims, players don't design their Singles from scratch, but choose from a selection of pre-made characters with various personality traits. As in Maxis' The Sims, players spend their time managing their character's day-to-day activities (such as going to work, eating regularly, and getting enough sleep), redesigning the apartment to make it more comfortable, and encouraging the two characters to grow closer by prompting them to communicate with one another in different ways.
Singles: Flirt Up Your Life is a personality simulation game that revolves around the development of a romantic relationship between two everyday characters, who begin as mere acquaintances sharing an apartment.