I know that VN engine is growing rapidly every year.
Just to list:
yum_puddi Belle yum_puddi Visual Novelty gaia_star Game Maker gaia_star CloudNovel gaia_star Renpy gaia_star RPG Maker emotion_bigheart Tyranobuilder yum_tea yum_strawberry yum_tea yum_strawberry yum_tea yum_strawberry yum_tea yum_strawberry yum_tea yum_strawberry yum_tea yum_strawberry yum_tea dramallama Game Maker is a powerfull engine for 2D game , like Flash game.
dramallama Cloud Novel is Web-based and have good publish/promote if you want to really focus on the story.
dramallama Renpy is an all aroud but required you to understand basic programming
dramallama RPG Maker is also powerfull 2D engine that have more variety in their battle system.
dramallama Tyranobuilder is very user friendly with drag and drop interference, so even a beginner who knows nothing of programing can still make VN game with it. this engine is my personal favourite, you can convert and publish your game in android, web,pc fairly easy too....
Anyone ever use Tyranobuilder? what do you think?