It’s incredibly easy to create your own visual novel, and many people do so with free or cheap programs that are widely available, intuitive and offer endless tutorials.
Ren’Py is the mostly widely used, and a good example for these kinds of programs:
Ren’Py is a visual novel engine – used by thousands of creators from around the world – that helps you use words, images, and sounds to tell interactive stories that run on computers and mobile devices. These can be both visual novels and life simulation games. The easy to learn script language allows anyone to efficiently write large visual novels, while its Python scripting is enough for complex simulation games.Ren’Py homepage, https://www.renpy.org/
Doki Doki Literature Club and Katawa Shoujo are two of the games made using Ren’Py.
Here are some more well-known visual novel game engines:
There are also programs that weren’t specifically invented to create visual novels but are extremely usable, especially if you want to incorporate multiple types of gameplay, like: