I downloaded this game to my Mac (Catalina) and trying to run it gave me a "The application 'Beneath a Withering Moon.app' can't be opened" error. It turned out that the main executable did not have execute permissions. Running the following:

chmod -x /Applications/Beneath\ a\ Withering\ Moon.app/Contents/MacOS/Beneath\ a\ Withering\ Moon

solved the issue and it runs fine now.