Per the below Apple developer reminder, Catalina apps need to be notarized for security. Now that 0.17 is stable, is it going to be submitted to Apple for notarization?
From:To further protect users on macOS Catalina, we’re working with developers to make sure all software, whether distributed on the App Store or outside of it, is signed or notarized by Apple. This will give users more confidence that the software they download and run, no matter where they get it from, has been checked for known security issues.
In June, we announced that all Mac software distributed outside the Mac App Store must be notarized by Apple in order to run by default on macOS Catalina. Make sure to test all versions of your software on the macOS Catalina GM seed and submit it to Apple to be notarized.
https://developer.apple.com/news/?id=10032019a
Edit:
This issue is tracked as 55063. It's currently on the "minor issues" list, but it might be about to become a "major" issue for macOS Factorio players given the impending release of Catalina. (The release candidate version of Catalina has already been released to developers, so the final version is due any day now.)
