http://osxdaily.com/2012/07/27/app-cant-be-opened-because-it-is-from-an-unidentified-developer/This might help.Jerry
Where did you get Chairgun for Mac?I can only find the Windows and Mac OS X versions, though no Macintosh version at all. I do have a couple of Macintoshes that I use a lot, one running Macintosh System Software 7.5.5, and one running Mac OS 9.2.2.