Based on the Advanced Dungeons & Dragons adventure Ravenloft by Tracy and Laura Hickman, Robinloft is and adventure module for characters level 5-7.
While the original module bore the designation I6, this Hackmaster version has no letter code.
From the publishers website:
"Welcome to Robinloft, a gloomy realm of despair and gothic horror. This HackMaster version of the classic Ravenloft adventure is sure to keep your players on edge with plenty of twists and turns as they try to escape from Count Vlad'Neer. This horrific module includes new monsters and other features that have helped make HackMaster the 2001 Game of the Year."