Commander Keen

In September 1990 John Carmack, programming for Softdisk's Gamer's Edge disk magazine in Shreveport, Louisiana, worked out "adaptive tile refresh," a trick that let an IBM PC scroll smoothly like a Nintendo Entertainment System instead of redrawing the screen in chunks. He and Tom Hall rebuilt the first level of Super Mario Bros. 3 overnight as "Dangerous Dave in Copyright Infringement," showed it to John Romero the next morning, then carried their work computers home for a weekend to build a full demo for Nintendo. Nintendo was impressed and declined: Mario stayed on Nintendo consoles.

Scott Miller of Apogee Software wanted a game for his shareware model, where the first part is free and the rest sold by mail, so the group, calling itself Ideas from the Deep, spent October to December 1990 making Commander Keen in Invasion of the Vorticons at night on Softdisk's machines. Hall drove the design. Keen is Billy Blaze, an eight-year-old genius with a homemade Bean-with-Bacon Megarocket, a raygun and a pogo stick, wearing the red shoes and Green Bay Packers helmet Hall wore as a kid. Miller uploaded "Marooned on Mars" to the bulletin boards on December 14, 1990, with the other two episodes mailed in a plastic bag of floppies for $30.

Apogee had been taking in about $7,000 a month; by Christmas Keen had brought nearly $30,000, and by June 1991 over $60,000 a month. The first royalty check convinced the team to quit Softdisk and found id Software in February 1991, after agreeing to keep making Softdisk a game every two months, one of which became the "lost" episode Keen Dreams. Goodbye, Galaxy arrived in December 1991 alongside the retail Aliens Ate My Babysitter and sold about a third of the original, which Miller blamed on splitting the trilogy. A third trilogy was planned, then dropped once Wolfenstein 3D hit.

Keen's afterlife runs on in-jokes. The Dopefish, "just a stupid green fish" from episode four, became one of the industry's most-referenced cameos, and Hall's Standard Galactic Alphabet, a cipher for hidden messages on signs, is the script on Minecraft's enchanting table. In 2018 Romero and Hall declared Billy Blaze the grandson of Wolfenstein's B.J. Blazkowicz and the grandfather of Doomguy.