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.
Unreal Engine - Unreal Engine 4 is a suite of integrated tools for game developers to design and build games, simulations, and visualizations.
Construct 2 - Scirra Construct is a 2D game development engine with a focus on building games visually.
Unity - The multiplatform game creation tools for everyone.
Stencyl - Make iOS (iPhone/iPad), Android, Flash, Windows & Mac games without code using Stencyl.