Doom (1993 video game)
The ability for others to create custom levels and otherwise modify the game using WAD files turned out to be a popular aspect of "Doom". Gaining the first large mod-making community, "Doom" affected the culture surrounding first-person shooters, and also the industry. Several future professional game designers started their careers making "Doom" WADs as a hobby, among them Tim Willits, who later became the lead designer at id Software.
Development of Doom
The initial concept for the game was proposed in the fall of 1992, after the release of "Wolfenstein 3D" and its sequel "Spear of Destiny". Lead programmer John Carmack was working on creating an improved 3D game engine from those games, and the company wanted to have its next game take advantage of his designs. Several ideas were proposed, including a new game in their "Commander Keen" series, but John Carmack successfully proposed a game about using technology to fight demons, inspired by the "Dungeons & Dragons" campaigns the team played, to be titled "Doom". The initial months of development were spent on prototypes, while Hall created several iterations of the "Doom Bible", a design document for his vision of the game and its story; after id released a grandiose press release touting features that the team had not yet begun working on, the "Doom Bible" was rejected in favor of a plot-less game with no design document at all.