Most visual Novels have multiple storylines and many endings; the gameplay mechanic in these cases typically consists of intermittent multiple-choice decision points, where the player selects a direction in which to take the game. This style of gameplay has been compared to the Choose Your Own Adventure novels. Most, however, strive for a higher level of plot and character depth than the aforementioned series of interactive children's books. These can be more closely compared to story-driven interactive fiction.
Content and Genre
There is a stereotype of: "Visual Novel = Dating Sim Game = Hentai", but that is wrong!
Visual Novels CAN be Dating Sim games, Ren'ai games, Bishoujo games, but also can be Sci-Fi, Fantasy, Adventure and Horror Fiction games, or anything your creativity comes up with :) Also, if you are creating Web Comic, Manga, or writing stories, you can easily turn them into Visual Novel.
Creating Visual Novel
Visual Novel usually consists of text window, background graphics and character graphics. In addition to those elements, music, sound and sometimes voice are added to make the VN more dramatic. It's SAVE and LOAD functions makes it easy to pause playing the Visual Novel when you want to come back later.
Producing Visual Novel is just like producing Japanese animation or Manga.
Good storyline is important, but also facial expressions of characters, their posing, the timing to use sound and screen effect are important elements to create interesting Visual Novel.
You don't need to be computer expert and have programming skill to create good Visual Novel.