You have to go to system preferences and press privacy and security. Go to the bottom and it will say open anyways about the application. Then it will work if you press it.
The dev should fix this issue, the app wasn't executable. To fix this open Terminal and change directory "cd /Applications/floppy\ minecraft\ mac.app/Contents/MacOS" and make the file executable by using this command"chmod 755 ./not\ minecraft\ dont\ sue\ me\ pls".
