Cocos2d-x is an open-source and cross platform open source free 2D game engine for mobile game development known for its speed, stability, and easy of use
Scirra Construct is a 2D game development engine with a focus on building games visually.
Sculptris: Enter a world of digital art without barriers.
GDevelop is an open-source game making software designed to be used by everyone.
The multiplatform game creation tools for everyone.
The Internet's free and open-source creation toolkit.
An open-source 3D/2D game engine for ObjectPascal.
Pygame is a set of Python modules designed for writing games.
Torque 3D is a easy-to-use game creation platform.
The most powerful game development platform is now available to everyone. Full engine source code.
Urho3D is a lightweight, cross-platform rendering and game engine implemented in C++ and released...
Unreal Engine 4 is a suite of integrated tools for game developers to design and build games, simulations, and visualizations.