It’s meant to be played on graph paper. The general idea is a randomly generated dungeon crawl. When you get to a door, you roll 1d6 and draw the next room! Each M is a monster, and each L is loot, which also has random tables to determine what is what, or you could use random tables from any other system with the general idea.
I would have Daggerfall flashbacks if I tried to map that 😅
You could do that as an alternative to finding stairs down - instead you find a gentle slope that goes under the previous tunnels, then start a new floor.