The way that I see it is that there are different styles of adult games. When it comes to visual novels I think there are 3 main types (not counting subsets, and splits like male vs female protagonist or NTR vs non NTR which these are other cans of worms I'm not going to get into).
Porn Visual Novel: A good example of a game like this would be game like "Family Affair" or "BadHero". The writing is not exactly at the level of the other two categories. Often times it could be Engrish. It's not going to be the most compelling story, but they will supplement that with a good amount of hardcore sex scenes. So the people looking to masturbate be able to spank the monkey.
Erotica Porn Visual Novel: Well written, and has hardcore sex good stuff. These sit at the top and are games like "Being a Dik" or "City of Broken Dreamers", or even "WVM" They will have build up, a nice interesting story ,and also a pay off without much wait.
Erotica Visual Novel: Also well written, but less hardcore sex, and more teasing. Games like "A Wife and Mother" or "Jessica Oneal's Hard News" come to mind. These games tend to drag out the seduction and teasing much longer than the Erotica Porn category.
What sort of reception do the 3 get?
Porn Visual Novels: These tend to get some criticism. People will bitch about a lack of story, or call it mediocre at best, or ENGRISH. It's usually fair criticism and not over the top. After all the guy did get his rocks off and moves along.
Erotica Porn Visual Novel: Generally generate very little hate. They tend to satisfy. A powerful build up with a powerful payoff. Well rounded compared to the other 2.
Erotica Visual Novel: Hate magnet... People just start stroking their dick waiting for that pay off just waiting and waiting and it pisses em off when they just keep teasing and teasing. They want so badly for this to be an "Erotica Porn Visual Novel". It's drives men mad and they lash out. However, they will also build up a strong base of defenders. The main reason for the hate is that "It angers people when they do not get what they want when they want it." The prolonged softcore and teasing get men riled up without release.
