Twine is an open source tool for buildig interactive narratives, choose-your-own-adventure stories, and point-and-click games. It has its own markup language, but users don’t need any previous coding knowledge, and the barrier to entry is very low.
Resources for Twine:
A trove of resources including tutorials, documentation, tools, etc.
How to Make Games with Twine by Auntie Pixelante
A step-by-step guide on getting started with Twine.
Guide to Twine markup.
Free Twine hosting for the web, so others can play your game!
“Ghost Burgers” by Anna Anthropy
“A Very Very VERY Scary House” also by Anna Anthropy