Doom (1993)

Doom is a 1993 first-person shooter (FPS) game developed by id Software for MS-DOS. Players assume the role of a space marine, popularly known as Doomguy, fighting their way through hordes of invading demons from hell. Id began developing Doom after the release of their previous FPS, Wolfenstein 3D (1992). It emerged from a 3D game engine developed by John Carmack, who wanted to create a science fiction game inspired by Dungeons & Dragons and the films Evil Dead II and Aliens. The first episode, comprising nine levels, was distributed freely as shareware; the full game, with two further episodes, was sold via mail order. An updated version with an additional episode and more difficult levels, The Ultimate Doom, was released in 1995 and sold at retail.
Doom is one of the most significant games in video game history, frequently cited as one of the greatest games ever made. It sold an estimated 3.5 million copies by 1999; between 10 and 20 million people are estimated to have played it within two years of launch, and in late 1995, it was estimated to be installed on more computers worldwide than Microsoft's then-new operating system, Windows 95. Along with Wolfenstein 3D, Doom helped define the FPS genre and inspired numerous similar games, often called Doom clones. It pioneered online distribution and technologies including 3D graphics, networked multiplayer gaming, and support for custom modifications via packaged WAD files. Its graphic violence and supposed hellish imagery drew controversy from different groups, such as parents and the news.
Doom has been ported to numerous platforms. The Doom franchise continued with Doom II: Hell on Earth (1994) and expansion packs including Master Levels for Doom II (1995). The source code was released in 1997 under a proprietary license, and then later in 1999 under the GNU General Public License v2.0 or later. Doom 3, a horror game built with the id Tech 4 engine, was released in 2004, followed by a 2005 Doom film. id returned to the fast-paced action of the classic games with the 2016 game Doom and the 2020 sequel Doom Eternal.
== Gameplay ==
Doom is a first-person shooter presented with early 3D graphics. The player controls an unnamed space marine—later termed "Doomguy"—through a series of levels set in military bases on the moons of Mars and in hell. To finish a level, the player must traverse through the often labyrinthine area to reach a marked exit room. Levels are grouped together into named episodes, with the final level focusing on a boss fight with a particularly difficult enemy. While the environment is presented in a 3D perspective, the enemies and objects are instead 2D sprites presented from several preset viewing angles, a technique sometimes referred to as 2.5D graphics or billboarding.
While traversing the levels, the player must fight a variety of enemies, including demons and possessed undead humans, while managing supplies of ammunition, health, and armor. Enemies often appear in large groups, and the game features five difficulty levels which adjust the quantity and damage done by enemies, with enemies moving faster than normal on the hardest difficulty setting. The monsters have very simple behavior, consisting of either moving toward their opponent if they see or hear the player, or attacking by throwing fireballs, biting, using magic abilities, or clawing. They will reactively fight each other if one monster inadvertently harms another, though most monsters are immune to attacks from their own kind. The environment can include pits of toxic waste, ceilings that lower and crush objects, and locked doors requiring a keycard or a remote switch. The player can find weapons and ammunition throughout the levels or can collect them from dead enemies, including a pistol, a chainsaw, a plasma rifle, and the BFG 9000. Power-ups include health or armor points, a mapping computer, partial invisibility, a radiation suit against toxic waste, invulnerability, or a super-strong melee berserker status. Cheat codes give the player instant super powers including invulnerability, all weapons, and walking through walls.
The main campaign mode is the single-player mode, in an episodic succession of missions. Two multiplayer modes are playable over a network: cooperative, in which two to four players team up to complete the main campaign, and deathmatch, in which two to four players compete to kill the other players' characters as many times as possible. Multiplayer was initially only playable over local networks, but a four-player online multiplayer mode was made available one year after launch through the DWANGO service.
== Plot ==
Doom is divided into three episodes: "Knee-Deep in the Dead", "The Shores of Hell", and "Inferno". A fourth episode, "Thy Flesh Consumed", was added in an expanded version of the game, The Ultimate Doom, released on April 30, 1995, two years after Doom and one year after Doom II. The campaign contains very few plot elements, with the minimal story instead given in the instruction manual and in short text segues between episodes.
In the future, an unnamed marine (known as the "Doom marine" or "Doom guy") is posted to a dead-end assignment on Mars after assaulting a superior officer who ordered his unit to fire on civilians. The Union Aerospace Corporation, which operates radioactive waste facilities there, allows the military to conduct secret teleportation experiments that go terribly wrong. A base on Phobos urgently requests military support, while Deimos disappears entirely, and the marine joins a combat force to secure Phobos. He waits at the perimeter as ordered while the entire assault team is wiped out. With no way off the moon, and armed with only a pistol, he enters the base intent on revenge.
In "Knee-Deep in the Dead", the marine fights demons and possessed humans in the military and waste processing facilities on Phobos. The episode ends with the marine defeating two powerful Barons of Hell guarding a teleporter to the Deimos base. Emerging from the teleporter, he is overwhelmed and comes to with only a pistol again. In "The Shores of Hell", he fights on through Deimos research facilities that are corrupted with satanic architecture and kills a gigantic cyberdemon. From an overlook he discovers that the moon is floating above hell and rappels down to the surface. In "Inferno", the marine takes on hell itself and destroys a cybernetic spider-demon that masterminded the invasion of the moons. A portal to Earth opens and he steps through, only to find that Earth has also been invaded. "Thy Flesh Consumed" follows the marine's initial assault on the Earth invasion force, setting the stage for Doom II: Hell on Earth.