I experienced a problem with the same symptoms, but on my end it seems to have evolved into something slightly different: (Can't get a Mac application bundle working).
I also followed the publishing steps Gronk suggested, but one possible hint is this sentence at the very bottom of them:
For archiving, we recommend using the .tar.gz format to preserve the execution permissions (you will likely run into permission issues if you use .zip at any point).
This hint correlates with this post, who experienced a similar issue: App packaging for Mac, The application "YourGame" can't be opened. - #2 by SquidJelly
On my end, I’m distributing the game via Steam. I have no idea what that means for execution permissions, but you should be able to confirm if that’s the issue by navigating to the MacOS subfolder under YourGame.app and running sudo chmod +x YourGame on the target machine.