Spring Engine - Spring is a versatile 3D RTS game engine.
Unreal Engine - Unreal Engine 4 is a suite of integrated tools for game developers to design and build games, simulations, and visualizations.
PlayCanvas - PlayCanvas is an open-source game engine built on WebGL and WebVR.
Unity - The multiplatform game creation tools for everyone.
Lips of Suna - Lips of Suna is a tongue-in-cheek action RPG.
Godot Engine - Feature-packed 2D and 3D open source game engine.