Quarterstaff: The Tomb of Setmoth

Infocom picked up this title as the first in their RPG line.  Originally self-published by Simulated Environment Systems as Quarterstaff (see there for details) exclusively for the Mac, Infocom spruced up the game, added a subtitle, added color for color Macs, fixed numerous bugs, and even changed the story somewhat.  They also added a Help window for hints, and various other handy gadgets.