This is pretty much what it says in the title, one feature and one bug fix:
Sandbox Mode
No longer do you have to fuss around with Git and Visual Studio Code to launch your own version of the game.
This allows you to always have the latest version of the game to experiment with and check out features, while not having to fiddle with development tools.
Bug Fixes
The Steam overlay would not take up the whole screenspace - this has been fixed (though is still a little janky!)