Twine - Twine is an open-source tool for telling interactive, nonlinear stories.
Godot Engine - Feature-packed 2D and 3D open source game engine.
Ink by Inkle - ink is a popular open source scripting language for branching stories, designed for writers
GDevelop - GDevelop is an open-source game making software designed to be used by everyone.
Squiffy - Squiffy is a tool for creating multiple choice interactive fiction.
Unity - The multiplatform game creation tools for everyone.