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.
Official versions of Doom
"Doom" is one of the most widely ported first-person shooter video games. Starting with the original MS-DOS PC version (released as shareware on December 10, 1993), it has been released officially for a number of operating systems, video game consoles, handheld game consoles, and other devices. Some of the ports are replications of the MS-DOS version, while others differ considerably, including modifications to the level designs and monsters, with some ports offering content not included in the original MS-DOS version.