happens to me too when playing on a Macbook Air. Sad because it used to be able to work but in these past few months it's stopped working.
actually it does work on catalina, in fact im playing it as we speak. How I got mine to work is:
1. Open terminal
2. Right click the app "The things we lost in the flood" and click on "Show package contents"
3. You'll see a folder called Contents. Double click on "Contents" and then "MacOS".
4. into terminal type "chmod +x " and drag and drop the file in the MacOS folder into terminal.
5. Press enter in Terminal and you should be good.
If you have any questions please let me know, I'd be glad to help.