Depths of Felk Mor

From the introduction:

Depths of Felk Mor is a supermodule designed for starting level characters, bringing them up to level 9 or 10 upon completion. This is a larger campaign, and not a singular adventure module to be completed in one or two sessions.
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This supermodule is designed to emulate the adventures, dungeon crawls, and campaigns of the early days of RPGs. This is done by capturing the play style, as well as trying to emulate aesthetics of those days.