Godot engine is a free and open-source game development software. It supports 2D and 3D games and unlike other engines like unity, 2D support is not just an orthographic camera. It allows developers to work in pixel coordinates. The 3D side of the engine is not that mature but it is ok if you want to create an OpenGL 2.0 game. It is now being rewritten for the upcoming major version 3.0.
While we are waiting for the awesome release of 3.0 which is planned for May/June 2017, we have the new 2.1.2 version released.
There are lots of fixes and updates in this version. One of them is the support for IPv6 which is now mandatory for developing for Apple devices. This new version adds ternary operations in GDscript and a 2D split screen functionality out of the box.
There are a lot of other bug fixes too that you can check it on the official website.