The founders of id Software met in the offices of Softdisk developing multiple games for Softdisk's monthly publishing, including Dangerous Dave. In September 1990, John Carmack developed an efficient way to rapidly side-scroll graphics on the PC. Upon making this breakthrough, Carmack and Tom Hall stayed up late into the night making a replica of the first level of the popular 1988 NES game Super Mario Bros. 3, inserting stock graphics of John 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 have potential. The team that would later form id Software immediately began moonlighting, going so far as to "borrow" company computers that were not being used over the weekends and at nights while they designed their own remake of Super Mario Bros. 3.
id Software has developed their own game engine for each of their titles when moving to the next technological milestone, including Commander Keen, Wolfenstein 3D, ShadowCaster, Doom, Quake, Quake II, and Quake III, as well as the technology used in making Doom 3. After being used first for id Software's in-house game, the engines are licensed out to other developers. According to Eurogamer.net, "id Software has been synonymous with PC game engines since the concept of a detached game engine was first popularized". During the mid to late 1990s, "the launch of each successive round of technology it's been expected to occupy a headlining position", with the Quake III engine being most widely adopted of their engines.