Godot Engine - Feature-packed 2D and 3D open source game engine.
Reality Factory - Reality Factory is a free suite of game development tools for building 3D games.
GDevelop - GDevelop is an open-source game making software designed to be used by everyone.
Project Anarchy - Project Anarchy is a complete end to end game engine and state-of-the-art toolset for mobile.
Unreal Engine - Unreal Engine 4 is a suite of integrated tools for game developers to design and build games, simulations, and visualizations.
Wicked Engine - C++ game engine focusing on modern rendering techniques.