That's not a sex game! (and if it is, I don't want to know about it... :S)
why would somebody need a standalone game about sex, when related mods exist for almost every modern rpg game?
On that note, why would someone want a game about real life stuff anyway?
In my mind, games should be a medium that allows me to experience a fantasy — that is something that doesn't happen every day. Fighting monsters, leading armies, magic, that sort of stuff. A game about sex or eating, or driving to work, or paying electrical bills doesn't sound appealing.
Of course such a game could have interesting gameplay mechanics, but the premise/story wouldn't be appealing at all.