Godot is an advanced, feature packed, multi-platform 2D and 3D game engine. It provides a huge set of common tools, so you can just focus on making your game without reinventing the wheel.
Godot is completely free and open source under the very permissive MIT license. No strings attached, no royalties, nothing. The users' games are theirs, down to the last line of engine code.
These details are provided for information only. No information here is legal advice and should not be used as such.