Guys, I found a way to continue playing FH if you updated your OSX. You don't have to downgrade, here's the thing: there's this brilliant invention called "PlayOnMac" and it allows Mac users to use ANY program meant for Windows, so all you have to do is get that downloaded and set up, add a new file, and use FH's WINDOWS download, from there, you'll be able to figure it out. Hope I helped!! Wink
Here's the link for PlayOnMac: https://www.playonmac.com/en/ (https://www.playonmac.com/en/)
Someone by the name of Argoo was able to figure out how the game can keep the running without having to downgrade the system.
Don't know much about MAC other than it won't run with the newer version but maybe you can give this a shot & if doesn't work , try converting it back to an older version as Kiki stated & as Wolfwaffles showed.