Hi. I had the same issue with running the game on Catalina. I found a workaround based on a recommendation for another game that has the same issue that can be found here https://itch.io/t/517191/macos-catalina-compatibility.
For me, double-clicking the app gave the error, "The application "morticianstale.app" can't be opened." So I had to open a terminal window, go to the folder containing morticianstale.app, type "cd morticianstale.app/Contents/MacOS", then "chmod +x morticianstale". Then when I tried to open it in the Finder again, I had to update my security preferences, but I am now able to run it.