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 files so death was permanent, the failed commercial ports that swapped the at-sign for a smiley face, and Rog-O-Matic, the 1981 Carnegie Mellon bot that beat the top human players.

• How BSD Unix and the curses library turned a scrolling text terminal into a two-dimensional canvas
• Why a tic-tac-toe grid kept randomly generated dungeons structurally sound and always solvable
• The save-scumming problem that led to consequence persistence, the mechanic now known as permadeath
• The Rodney joke hidden in the Amulet of Yendor, and why abstract ASCII symbols made the game scarier than graphics
• How refusing to release the source code inspired Hack and Moria and gave the roguelike genre its name