Does DEFCON support OSX Mountain Lion 10.8?
If you download a fresh copy, Gatekeeper will tell you that DEFCON is from an unidentified developer. The game runs fine though if you tell OS X to ignore that, though, or if you've got DEFCON already installed.
DEFCON works fine on my Mountain Lion installation.
Thanks to you, I played my first game of DEFCON in a very long time. 80 million killed to 1.4 million. Woot!