You could try the following:
First, open a terminal to the folder you put the application in (it might be ~/Applications)
Then run:
chmod +x "Apparatus- Exanimus.app/Contents/MacOS/Apparatus- Exanimus"
Then finally try running the application again
Tried this, on my original download and a new download. But it did not work
In that case apologies, I'm not sure what more I can do - I'm unable to reproduce. I've found MacOS to be notoriously tricky to support - sorry
No worries, I develop with Mac so I'm well aware of the headache. Looking forward to playing this if I can get this sorted out!
