Dungeons & Dragons inherited random tables from wargaming, but took it much further. As noted in Playing at the World–a history of the development of D&D–wandering monster tables, such as the one above from B2: The Keep on the Borderlands, greatly expanded on the mechanic from Outdoor Survival. Every turn in the dungeon, there’s a 1-in-6 chance of meeting a wandering monster. Further checks determine which kind of monster, if it’s surprised, and so on.

And procedural generation wasn’t restricted to the monsters you might meet. Random dungeon generation has been a part of D&D for a very long time. In 1975, the first issue of Strategic Review (TSR’s precursor to the Dragon magazine) features a random dungeon generator for solo adventures. In Playing at the World, author Jon Peterson draws a connection between these random tables and the early dungeon crawlers on the PLATO system.