id Software is an American computer game developer based in Mesquite, Texas, a suburb of Dallas. The company was founded by four members of the computer company Softdisk: programmers John Carmack and John Romero, game designer Tom Hall, and artist Adrian Carmack (no relation to John Carmack). It is now considered the most influential of the many game development companies in the Dallas area, known as the Dallas Gaming Mafia.
The founders of id Software met in the offices of Softdisk developing multiple games for Softdisk's monthly publishing. These included Dangerous Dave and other titles. In September 1990, John Carmack discovered an efficient way to perform rapid side-scrolling graphics on the PC. Upon making this breakthrough, Carmack and Hall stayed up late into the night making a replica of the first level of the popular 1990 NES game Super Mario Bros. 3, inserting stock graphics of Romero's Dangerous Dave character in lieu of Mario. When Romero saw the demo, entitled "Dangerous Dave in Copyright Infringement", he realized that Carmack's breakthrough could mean fame and fortune, and the id Software guys immediately began moonlighting, going so far as to "borrow" company computers that were not being used over the weekends and at nights while they whipped together a full-scale carbon copy of Super Mario Bros. 3 for the PC, hoping to license it to Nintendo.
Despite their work, Nintendo turned them down, saying they had no interest in expanding to the PC market. Around this time, Scott Miller of Apogee Software learned of the group and their exceptional talent, having played one of John Romero's Softdisk games, Pyramids of Egypt, and contacted Romero under the guise of multiple fan letters that Romero came to realize all originated from the same address. When he confronted Miller, Miller explained that the deception was necessary since companies at that time were very protective of their talent and it was the only way he could get Romero to initiate contact with him. Miller suggested that they develop shareware games that he would distribute. As a result, the id Software team began the development of Commander Keen, a Mario-style side-scrolling game for the PC, once again "borrowing" company computers to work on it at odd hours at the lake house at which they lived in Shreveport, Louisiana. On December 14, 1990, the first episode was released as shareware by Miller's company, Apogee, and orders began rolling in. Shortly after this, Softdisk management learned of the team's deception and suggested that they form a new company together, but the administrative staff at Softdisk threatened to resign if such an arrangement were made. In a legal settlement, the team was required to provide a game to Softdisk every two months for a certain period of time, but they would do so on their own. On February 1, 1991, id Software was founded.
The shareware distribution method was initially employed by id Software through Apogee Software to sell their products, such as the Commander Keen, Wolfenstein and Doom games. They would release the first part of their trilogy as shareware, then sell the other two installments by mail order. Only later (about the time of the release of Doom II) did id release their games via more traditional shrink-wrapped boxes in stores (through other game publishers).