Dennis Ritchie, co-developer of Unix, reportedly called it the biggest waste of CPU cycles in history: a 1980 game built entirely from punctuation marks that had the brightest minds in university computer labs hunting for the Amulet of Yendor on multimillion-dollar mainframes. This episode tells the story of Rogue, its creators Michael Toy and Glenn Wichman at UC Santa Cruz, and how a grid of letters and symbols quietly invented the design rules behind Hades, Spelunky, and FTL.

We trace Toy's childhood visits to a nuclear laboratory mainframe, Wichman's Dungeons and Dragons background, the replayability problem they saw in Colossal Cave Adventure, and the curses library from Ken Arnold that let them freeze characters on a terminal screen. From there: the hidden three-by-three grid behind procedural dungeons, the decision to delete save file ...