It's all done by drawing cards. Each part of the dungeon is generated by drawing a card, as are wandering monsters etc etc.
The "AI" of the monsters is created by following rules such as "monsters attack equal number of heroes". So if there are 4 monsters and 4 heroes in range, they all get attacked by 1 monster each.
I made my own cards up by sticking address labels on some playing cards and writing the name of each section in permanent marker
