Construct 2 - Scirra Construct is a 2D game development engine with a focus on building games visually.
Twine - Twine is an open-source tool for telling interactive, nonlinear stories.
MonoGame - MonoGame is an open source implementation of the Microsoft XNA 4 Framework.
RenPy - Ren'Py is a free and cross-platform visual novel engine that helps you use words, pictures, and...
Godot Engine - Feature-packed 2D and 3D open source game engine.
Quest - Quest lets you create sophisticated text-based games, without having to program.