Godot is a free, open-source, and MIT licensed game development environment for 2D and 3D games.
Pro Friendly towards Version Control Systems
The engine is build not only to support version control but to really use it. Scene files for example which usually get compiled into some sort of unreadable data stay in a text format - that way you can actually see your changes in a version control system like Git.
Pro Easy to learn scripting language
It can be used to add custom behaviors to any object by extending it with scripting, using the built-in editor with syntax highlighting and code completion.
A built-in debugger with breakpoints and stepping can be used and graphs for possible bottlenecks can be checked.
Pro Under constant development
This engine barely released one year ago has more than 1000 forks on github and about 100 developers. Not only that just a bit of browsing trough issues you will quickly find out the dev community loves new esp free technology and does not shy away from completely rewriting parts of the engine. The audio engine is being completely rewritten to use threads and so forth.
Pro Internationalization of the editor
You can change the language shown in menus. Godot translations: https://hosted.weblate.org/projects/godot-engine/godot/
Con Difficult to optimize
Godot has an OOP architecture. Everything is an object internally and data is spread among many classes, thus it's difficult to optimize (i.e. not cache friendly, difficuly to vectorize or paralellize, etc).
Read about "Data Oriented Design" for more info about the problems and solutions.