ID Software created Commander Keen, Wolfenstein 3D, Doom, and Quake. They popularized the genre of first person shooters & in some cases even provided the original code that games like Half Life and Call of Duty where built on. They would go on to popularize multi-player in first person shooters. John Carmack and John Romero went their separate ways in 1996. John Romero went on to form Ion Storm and create Daikatana, & have Deux Ex produced through his company. John Carmack continues to lead ID Software & continues to work on new projects like Rage and Doom 3 bfg edition, along with his private company armadillo aerospace.