Yarnspin is a game engine which is very specialized on story telling. It is specifically made for authoring choose-your-own-adventure style computer games, with images, text, music and sound.
Yarnspin had its own scripting language, which is very simple and made for story tellers, not for programmers. It is not much more complicated than writing a screen play.
You can try the tutorial game at the top of this page. It shows what a Yarnspin game plays like, and it also explain some of the fundamental concepts.
If you want to start building a game yourself with Yarnspin, please download the zip file for your platform, and open the yarnspin.pdf file for instructions.
The source code is available on github: https://github.com/mattiasgustavsson/yarnspin
There is now a discord server for Yarnspin. For anyone interested in chatting about it, get answers to questions, or chat about story-games/interactive fiction/visual novels/etc, feel free to join here:
Games made with Yarnspin
In addition to the example/tutorial game above, here are a couple of games I have made with Yarnspin. They can be played in the browser, right here on itch:
Download the zip file for your platform, and unzip all the files anywhere. Open the file yarnspin.pdf for further instructions.