this.
you can never have the map fully explored because next time you start a game it will be a completely new and randomly generated map.
Indeed....I got massivley confused last night on Act 2 in the desert....I got disconnected after getting near the end of 1 section, after re-connecting I was put back to the begginning near the hidden town, after trying to re-trace my steps I found everything had changed and it really threw me off....quite clever.