The Wizard's Castle

I'm not sure The Wizard's Castle counts as interactive fiction. Rather, it's a text-based RPG with a keyword parser. If anything, it has more in common with Super Star Trek on the one hand, and roguelikes on the other. Prose is nothing to write home about either, though it makes an honest effort to set the mood thought ambient messages. The Z-Machine port is arguably an abuse thereof, since any story is going to be emergent, and only happen in the player's mind. Rules resemble those in Eamon, a game of similar vintage and origin, though much more popular and influential.

Still, it's easy to see why The Wizard's Castle also became a cult classic. Worth a try.