Quarterstaff

You are Titus.  You must build a lead a party of adventurers into the Tree Druid colony to discover the fate of recently vanished inhabitants.

This game is one of the first RPGs designed specifically for the Mac computer, and takes full advantage of its interface using pull down menus and windows extensively, including a auto-mapping feature.  Commands can also be input like a standard text adventure and it had a reasonably sophisticated parser.

Infocom later bought the game rights, touched it up and republished it as Quarterstaff: Tomb of Setmoth.