Eye of the Serpent (1984)

From the back cover:

"Gazing down from the pinnacle of Hardway Mountain, who would not be drawn by the far-off glint of the Serpent's Eye? The descent will be hard, the mountain knows neither mercy nor compassion. Many are the lessons to be learned, but fate has left you little choice - are you equal to the challenge?

Eye of the Serpent is a one-on-one wilderness adventure module for one player and one Dungeon Master, and has been designed to develop the specialist skills of a first level druid, ranger, or monk character. It can also be used for a normal party of 4-6 first level player characters.

The perils of Hardway Mountain are unchanging, but the routes between them are not. This module includes a unique route planning system with different routes linking the encounters to challenge the abilities of druids, rangers, or monks. Alternately, Dungeon Masters can change the routings to create their own original and exciting adventures."