You start, alone on a small boat when the island of Yah-Mon breaks the surface under you. In the confusion your small boat is lost and you are stranded on this island. Search for and survive the Citadel of Yah-Mon, man and defeat the sorcerer within, then escape the island safely.
Notes
The game itself is dated 1989. Like David R. Moffatt's other games, this is likely to have been published elsewhere prior to the much later Guild release.
The "READ ME" in the program itself mentions contacting the author directly in Pine City for a solution.