Eroge / Dating Simulators is actually a pretty wide genre all by itself, with really no equivalent in the west (well, one could make an argument for video game text rpgs like Zork, but who plays those?
).
I'm talking off of the top of my head here, so people who are more familiar with this genre, please feel free to expand or correct me.
You've got series like the aforementioned
Air, whose main focus is on the story and not on gettin' it on with the girls. In fact, later versions of the game and the series edit out most of, if not all, the porn. Same goes with
Kanon, the game made by the same time prior to Air.
Then there's ones with a lot more focus on teh pornz, like Xchange (which I'm not going to hunt down a link to, because I'm writing this at work and don't feel like having sysadmins jumping all over me) but is really, really frigging silly. Basically, you're a boy turned into a girl, and you get yourself into all sorts of situations in order to change back (or you accept it;
Mandy's Law of Anime Gender Bending at work). It's a mixture between consent and no consent, but it's so weird and over the top that you can ignore a lot of the ickier implications.
When I talk about consent in these situations, by the by, I mean consent in-game, between you and the pixels. Yes, it's a weird concept to roll through your head, but as computer AI increases...
And then there's Bible Black and / or Mahou Shojo Ai (I *think* I'm getting that one right, and if you think I'm linking to either of those, you're crazy) which is basically an excuse for porn, weird porn, and oh my god porn. Consent is definitely not involved in these (barring some crazy side hookups, iirc).
As Kage said, this is analogous to the FPS genre here in the west and its wide range of what's out there. There's stuff like Mirror's Edge, which advocate jumping and dodging and avoiding direct conflict, to Halo who's direct, balls on hoo-yah Marine stuff, and the Tom Clancy games, which are a lot more tactical and cerebral. They're all part of the same "genre", but they don't much resemble each other other than they're in first person and you use guns to shoot people in the face.
And before anyone accuses me of being a dirty, perverted otaku, you pick this stuff up if you're familiar with the anime subculture. Air / Kanon got a lot of attention in the west because of Megatokyo, and the other three are rather popular if you're familiar with the
Site That Shall Be Named.
So...yeah.