Ah I understand. Someone had given me the advice to design for example a natural location. Let's say a castle. As if it where really a castle, multiple corridors and rooms as if it was built for its original purpose. So multiple ways to get around the entire place. Not a straight line.

Then infest it with encounters, logical traps, roleplay elements that come up either along with or because of the infestation.

This leaves it both believable and more interesting.