Zork II: The Wizard of Frobozz (1981)

Frobozz's underground world makes a labelled route graph more useful than a tidy architectural floor plan. Some places deliberately interfere with normal assumptions about direction, so annotate an exit's conditions before treating it as a permanent connection. The wizard can also disrupt your plans. Available in The Zork Anthology, this is a tougher follow-up for someone who enjoys testing a map against the text, with saves before risky experiments rather than an expectation of forgiving modern recovery.