From the publishers blurb: This is an old-school sandbox adventure for the basic version of the world's most popular fantasy RPG, suitable for characters of levels 1-3. Explore the wilderness and the three detailed dungeons around the human outpost of Fort Perilous. On the border between wilderness and civilization, Fort Perilous stands, keeping watch and holding the forces of Chaos at bay. Your heroes find themselves in the fort, drawn into the battles between civilization and monsters, between Law and Chaos. This module is compatible with the B/X and Labyrinth Lord rules and is published under the Open Game License (OGL)