Twine - Twine is an open-source tool for telling interactive, nonlinear stories.
microStudio - microStudio is an all-in-one online game engine that enables you to create games, develop programming skills, have fun playing what you have created, share with others, and prototype.
Ink by Inkle - ink is a popular open source scripting language for branching stories, designed for writers
Godot Engine - Feature-packed 2D and 3D open source game engine.
Quest - Quest lets you create sophisticated text-based games, without having to program.
ENIGMA – LateralGM - LateralGM is a powerful IDE for ENIGMA, and both of these combine to offer you a cross-platform game environment.