The first thing I tried was to right-click on the installer and select 'Show Package Contents.' Then, under 'Contents' > 'MacOS,' you'll find the Diablo III Setup executable. Double-click it and you should see a Terminal window pop up and quickly disappear. You may not be able to see what has caused the problem, but it should have reported a permissions error ('Permission denied').
To fix this, open a Terminal window and navigate to the directory where you put your installer (for me it was Downloads; the easy way to get to it is to type 'cd ' [that's the letter c, the letter d and a space] and then drop the desired folder onto the Terminal window and hit 'enter') and type (include the quotes here):
sudo chmod -R 777 "Diablo III Setup.app"It will ask for your password and, once authenticated, it should fix your permissions issue.
At this point, you can try double-clicking on the installer and you should be in business.
If, however, it tells you that your video card is not supported (like me), you will have to do a little more work. No biggie.
Open a terminal and type:
nano ~/Library/"Application Support"/Blizzard/"Diablo III"/D3Prefs.txtYou should see a bunch of options, followed by values, like this:
DisableTrilinearFiltering' and change its value from '0' to '1,' then do the same thing for the option 'HardwareClass.'
It may not be required for everyone, but I also had to add an option, 'DisplayModeWindowMode,' with a value of "1."
Now, save and close by hitting Ctrl+x and then 'enter.'
You should be good to go :)
And, I assure you, performance *will not* be a problem (this is meant as a joke; of course performance will be a problem; it hardly runs, ffs).