The 0.52.1a release is now available. It’s a point release and doesn’t contain any significant new features, but it does have a number of important bug fixes, some enhancements to the modding API, and a few usability improvements.
The full patch notes are here.
This version is save-compatible.
You can download it using the buttons below. You’ll have to reinstall the game, but shouldn’t need to enter the activation code again.