unlike most published adventure modules, the "expedition to the ruins of greyhawk" is technically an incomplete "open ended" adventure. rather than detailing every single room of the dungeons below the ruins, only key areas that affect the main plot of the adventure are detailed. in fact, entire dungeon levels are left unmapped and the dm is encouraged to improvise their own encounters to fill in areas not covered by the game with their own content. the game provides a list of random encounters for each dungeon level, generic dungeon maps left clear of content, and numerous side quests to help the dm along the way and keep the adventure flowing.