K, I'll take this from fhc's NTR thread and post a part of it here for ya Cursed and Blue. *ahem*
What is NETORARE ( 寝取られ ) ?
NETORARE ( 寝取られ ) also named just like "NTR" ( Abbreviation ) is a genre of EROGE. "eroge" means "Japanese erotic game" , called generality like "Hentai Games" in Westerner World.
The unique objective of NTR is to play with the "jealous feelings" of the player.
In NTR games you play like a MALE PROTAGONIST that love a girl in the game. However, for some reason, this girl BETRAY the protagonist and make sex with other guy.
Exist 3 kinds of NTR :
NTR kind A ( consensual sex )
the girl that the protagonist love agree to make sex with other guy instead of the protagonist in the game, she is not forced, she want it, is NOT a rape .
NTR kind B ( semi-consensual sex )
the girl in the beginning of the game is really raped, but, during the gameplay this rape begin to change gradually to consensual sex, because the girl begin to like it a lot
in this kind of game ( kind "B" ) , are listed games that are used some kind of "trick" to make the girl to make sex with others guys instead of the protagonist, like hypnotism, aphrodisiac or sometimes even brainwash . All games with NTR related with this kind of "feature" are considered "kind B".
NTR kind C ( violent rape without pleasure )
the girl is raped - she resist until to the last minute, she never agree with this and she never feel pleasure during this sexual act , she feel only pain and suffer, this is just a violent RAPE really .
And there's your history lesson ^^ I'm the B type lover.