13 years ago today DOOM is released. widely recognized for its pioneering use of 3D graphics, networked multiplayer and custom expansions creations, DOOM is one of the landmark games that popularise the First Person Shooter genre.
Distributed as shareware, Doom was downloaded by an estimated 10 million people within two years. As a sign of its impact on the industry, games from the mid-1990s boom of first-person shooters are often known simply as "Doom clones".
summarised from wikipedia