Exploring the archives of the People's Computer Company (a public timesharing computer center in the early '70s, yes before home computers), and many of the programs we're familiar with from David H. Ahl's Creative Computing come from here. 15 different variations on guess the number and guess a coordinate, sure, but also some really important things, many of them long forgotten.
Then I find this artifact:
What the. This is basically a MUD†, from 1973!
Source code (uses a very long TREES library on previous pages).
Everyone knows WUMPUS, which is based on CAVES, but this is the rock star of these! How does everyone not have a copy of PCAVES? This is like finding a working Airwolf helicopter in a cave with ochre handprints on the walls. HOW THE FUCK did cavemen do that? Why don't we all have an Airwolf, if it existed 47 years ago?!
So anyway some barely-modernized version of this will be added to the MysticDungeon soon, you'll all be able to graffiti up a cave!
† more like a MUSH ("Multi-User Shared Hallucination") with one user at a time, specifically.