I have fond memories of playing this with a friend - taking turns mapping and controlling the game. So much grid paper :) That, and cleaning up the maps when you ended up walking off the edge of the paper (most levels would fit on one to two sheets of a4 grid paper IIRC - but only if properly centered).
There were also maps floating around on usenet(?) and walk-through published in magazines.
Back in those ancient times you were supposed to have grid paper and pencil ready to draw the map yourself while exploring :)