Doom was the 1993 PC game that popularized the modern first-person-shooter deathmatch.
id Software developed Doom under the leadership of John Carmack and John Romero. It casts the player as a space marine fighting demons on the moons of Mars, combining fast movement, maze-like levels, weapons, secrets, and horror imagery.
The game was distributed using a shareware model: the first episode was made widely available, while additional episodes were sold. Doom also supported networked multiplayer, including competitive deathmatch and cooperative play, helping establish a lasting multiplayer vocabulary.
Doom is often called the game that “invented” the first-person shooter, but that is not literally correct. Earlier games, especially id’s Wolfenstein 3D and titles such as Maze War, had already established important parts of the genre.