I'm running Catalina and can't open the game either.
Thanks, actually I was able to get it working by doing these 2 things:
1. Used 'xattr' to clear the 'quarantine' attribute on the package (this is a common fix for 3rd party software with modern macos).
2. Looked inside the package and used 'chmod' to change the 'pipepushparadise' file to be executable.