We don't believe every player should have to be a tester. On the other hand, if we had to keep the game at an ever perfectly stable state, we'd never make any progress. So, we're doing something here that'll hopefully allow us to move forward, without forcing everyone to endure the inevitable bug or thousand that comes with a game that's still under heavy continued development.
Enter "Previous Releases". It is now possible to roll back your game to the previous version at any time you want.
Here's how it works:
* If you have the game on the KSPStore, you'll now find two sets of buttons to download the game. One for the latest release, and another for the previous version. Download and install whichever one you prefer.
* If you have the game on Steam, you'll find a Beta branch on your Steam Game Settings for KSP, called 'previous'. Opting in to that branch will downgrade your install to the previous version. Changing back to the default branch will upgrade you back to the latest version.
This way, if you find a new update has made something incompatible, or if it's too buggy for you and you want to wait for a more stable patch, you can opt to keep the old version a while longer.
So, here's a few probable FAQs:
Q: Are Previous Versions bug-free?
Most likely not. Keep in mind KSP is still a work-in-progress, so even though these are more stable builds, it does not by any means guarantee a bug-free experience.
Q: Can I load saves from the latest version on the previous one?
Reverting back to a previous build will break forward-compatibility with saves from the later versions. (You can't load a save from 0.20 in 0.19, for instance). Supporting this would require time travel. If you've got a working implementation of time travel however, do let us know.
Q: Will mods for the newer versions work on the previous one?
Maybe. Most likely not. It depends on the type of mod (part packs are usually more resistant to change than plugin-based mods), but really, if a mod had to be updated to be compatible with the new version, it probably won't work anymore on the old one.
BTW, If you didn't see it already, the 0.20.1 patch is out!