Preceded by Apple's late-80s failure with the "Pink" OS:
http://lowendmac.com/2014/pink-apples-first-stab-at-a-modern...
http://lowendmac.com/2014/pink-apples-first-stab-at-a-modern...
Source: I worked on Pink/Taligent for six years. Prior to that I supported A/UX and MPW in MacDTS.