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.
Doomguy
The Doomguy, commonly known as the Marine and referred to as the Doom Slayer in the rebooted portion of the series, is the unnamed player character in the "Doom" video game franchise of first-person shooters created by id Software, and its sequels and spin-off media. He is a space marine dressed in green combat armor who does not speak onscreen.