I wonder if anyone heard about.
Originally developed by Okam Studio; Godot Game Engine is an advanced 3D/2D game engine/editor, export to Linux, OSX, Windows/WinPhones, Android, iOS and some consoles (not publicly available, because console's SDK aren't) and HTML5 on redo (switching from emscripten to webasm)
License: MIT. Take the editor/engine/binary/sources and do whatever you want. Absolutely free of charge
Other than the online help (directly in the editor) there's a wiki and some video tutorials
Also this youtuber made several tutorial about Godot
Editor download are for Windows, Linux e OSX