Games of this nature have been around for a long time in Japan. They're known as "eroge" or "galge." There's not much difference in the terms, but the games range from just trying to date someone to full-blown rape. The games are generally pornographic in nature, but not always. I (a girl) have played some of these games, not because of the pornography, but because they are games that have subtleties rarely found in other, more violence based games.
At their basest, they are simply text-based adventure games with a very narrow set of goals.