Godot Engine is one of the best Game Engines World Wide compared to Unity/Unreal/Cryengine. It is completly Free & Open Source and offers you many great tools.
You can Develop and build Games on Windows, Linux and Mac OS.
The Development interface is flexible and has Nodes for all you needs, Visual Editor, it offers you to create custom tools, ...
What about the Programming?
It offers you GDScript that is a Python like scripting language, that is easy to use and offers good performance.
It also have Full C# 7.0 Support, Full C++ Support, Visual scripting, additional languages provided by the community.
What about the Graphics?
It has Physically-based rendering with full MSAA support, Global illumination, Easy to use shader language,
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The Engine currently offers GLES3/GLES2 and with the version 4.0 it will have support vulkan that could be released 2020.
What about Export?
It offers many export options such as Android, IOS, Html 5 (Webassembly), Mac OSX, Windows Universal(Windows 10/ ...), Windows Desktop (Windows 10/8/7).
Whats my Opinion?
I would definetly recommend to check out this Game Engine, in my experience it is one of the best game engines, that has allowed me to write small code, fast performance, cross platform, and with that it allowed me as a hobby developer to create a small multiplayer first person game.
If you wanna try it out yourself or get more information here is a link : https://godotengine.org/
You can also find many tutorials on youtube on how to create a game and how to use the Godot Engine.
