Delver is set in an old dungeon simply named "The Dungeon". The Dungeon has 6 randomly generated floors, followed by a static end-game floor. Floors 1 and 2 are called Dungeon floors, floors 3 and 4 are the Cave floors, floors 5 and 6 is the Sewer, and floor 7 is the final level being the Ruins . This dangerous final floor is where the Lich and Orb are found.
Each floor deeper is harder than the last, having better loot and stronger monsters, with certain enemies only on different floors. The character cannot exit the dungeon without the Yithidan Orb, so he must progress all the way down, defeat all the creatures, and recover the orb in order to escape successfully.