Godot Engine - Feature-packed 2D and 3D open source game engine.
GDevelop - GDevelop is an open-source game making software designed to be used by everyone.
Cyberix3D - Free online 3D Game Maker. Make your own 3D games online!
MonoGame - MonoGame is an open source implementation of the Microsoft XNA 4 Framework.
Unity - The multiplatform game creation tools for everyone.
Unreal Engine - Unreal Engine 4 is a suite of integrated tools for game developers to design and build games, simulations, and visualizations.