As the title says, I overwrote a newer version of a game I made with an old one. This has removed the majority of the content I added, and is a crushing loss. I have some test files I made, though. Not quite from the newest version, but they contain most of what I lost. Seeing as they still play as independent files, they must contain the source code. Is there a way to extract that?

Actually scratch that.
I have no clue what's happened since the last time I opened it, but it's back to the new version again.