In September 1990, a small software company called IFD ("Ideas From the Deep") created a version of Super Mario Bros. 3 for the PC. Running on DOS, the game was just a proof-of-concept: Mario could run, jump, collect coins, and use power-ups, visit the world map, and interact with enemies. Many details of the Nintendo version's gameplay (like Raccoon Mario's flight behavior) worked differently—though it was clear that the core game could be made to work on PCs, not just the Nintendo Entertainment System.
Nintendo declined to pursue a PC version of Super Mario Bros., so IFD quickly pivoted, reusing their side-scrolling game engine to create the classic shareware game Commander Keen. (IFD also changed its name to id Software, leaving the "id" intentionally lowercase.) Commander Keen turned 25 this week, and id cofounder John Romero posted this rare play-through of IFD's original Super Mario Bros. 3 PC game on Vimeo. Behold this odd side-quest in gaming history:
Also note how the soundtrack on this demo version doesn't match up with the Nintendo game. It's a great lesson in what gives the Nintendo game its flavor—without the music and with very basic PC-style bleep/bloop sound effects, SMB 3 feels just a bit cheap.
After using this game engine for Commander Keen, id Software went on to make a few games you might have heard of, including Wolfenstein 3D, Doom, and the Quake franchise. So things worked out pretty darn well for them despite scrapping the Mario game. This week, id cofounder Tom Hall also released a Commander Keen-style level made in Super Mario Maker for the Wii U. The circle is complete!
(Note: For a bit more on this game's history, check out the "Dangerous Dave in Copyright Infringement" YouTube video, in which Romero's Dangerous Dave character is inserted into a semi-functional Super Mario Bros. world. For more on that game, check out Romero's writeup recalling his astonishment on seeing the smooth side-scrolling engine created by John Carmack and populated by Tom Hall.)