Doom (video game)

"DOOM" redirects here. For other uses, see Doom (disambiguation).

Doom
Box art, painted by Don Ivan Punchatz.
Developer(s)	id Software
Publisher(s)	id Software GT Interactive (Windows, Mac, Saturn) Activision (GBA, XBLA) Atari (Jaguar) Sega (32X) Valve Corporation (Steam) Williams Entertainment (SNES, PSX) Ocean Software (PAL SNES) Imagineer (SFC)
Director(s)	Tom Hall
Designer(s)	Sandy Petersen, John Romero, Shawn Green
Programmer(s)	John Carmack, Mike Abrash, John Romero, Dave Taylor
Artist(s)	Adrian Carmack, Kevin Cloud
Composer(s)	Bobby Prince
Series	Doom
Engine	id Tech 1
Version	1.9
Platform(s)	DOS ...more
Release date(s)	December 10, 1993 PC & MAC NA December 10, 1993 EU 1993 Sega 32X NA 1994 EU 1994 JP December 3, 1994 Atari Jaguar NA 1994 SNES NA September, 1995 EU October 26, 1995 JP March 1, 1996 PlayStation NA November 16, 1995 EU December, 1995 JP April 19, 1996 3DO NA 1996 JP April 26, 1996 Sega Saturn NA March 31, 1997 EU 1997 JP July 11, 1997 Game Boy Advance NA October 28, 2001 EU November 16, 2001 Xbox Live Arcade NA September 27, 2006 EU September 27, 2006 JP September 28, 2006
Genre(s)	First-person shooter
Mode(s)	Single-player, multiplayer
Rating(s)	BBFC: 15 CERO: C,D ESRB: M, T (GBA) OFLC: MA15+ PEGI: 16+ USK: 16+ (re-rating 2011) / 16+ (GBA version)
Media/distribution	3½-inch & 5.25-inch floppy disks, CD
System requirements 80386 class CPU, 4 MB[1] RAM

Doom (typeset as DOOM in official documents)^[2] is a landmark 1993 first-person shooter video game by id Software. It is widely recognized for having popularized the first person shooter genre, pioneering immersive 3D graphics, networked multiplayer gaming, and support for customized additions and modifications via packaged files in a data archive known as "WADs". Its graphic and interactive violence,^[3] as well as its Satanic imagery, also made it the subject of considerable controversy. In Doom, players assume the role of a space marine who must fight his way through a military base on Mars' moon, Phobos, and he must kill the demons from Hell.

With a third of the game (9 levels) distributed as shareware, Doom was played by an estimated 10 million people within two years of its release, popularizing the mode of gameplay and spawning a gaming subculture; as a sign of its effect on the industry, games from the mid-1990s boom of first-person shooters are often known simply as "Doom clones". According to GameSpy, Doom was voted by industry insiders to be the greatest game of all time in 2004.^[4] The game was made available on Steam on August 3, 2007.^[5]

The Doom franchise was continued with the follow-up Doom II: Hell on Earth (1994) and numerous expansion packs, including The Ultimate Doom (1995), Master Levels for Doom II (1995), and Final Doom (1996). Originally released for PC/DOS, these games have later been ported to many other platforms, including nine different game consoles, Rockbox firmware, and even PDAs and the Flash Player virtual machine. The series lost mainstream appeal as the technology of the Doom game engine was surpassed in the mid-1990s, although fans have continued making WADs, speedruns, and modifications to the source code released in 1997.

The franchise again received popular attention in 2004 with the release of Doom 3, a retelling of the original game using new technology, and an associated 2005 Doom motion picture. On May 7, 2008, following speculation by John Carmack at QuakeCon on August 3, 2007, Doom 4 was announced as in production. The game is neither a sequel to Doom 3 nor a new beginning of the franchise and it will use the company's new id Tech 5 engine. On June 26, 2009, John Carmack released Doom Resurrection, a new game developed by Escalation Studios for iOS and published by id Software. The setting for Doom Resurrection takes place parallel to Doom 3, and it uses the characters and art from the previously developed game.

Game features

Plot

Doom, a science fiction/horror themed video game, has a background which is given in the game's instruction manual; the rest of the story is advanced with short messages displayed between each section of the game (called episodes), the action as the player character progresses through the levels, and some visual cues.

The player takes the role of a unnamed space marine who has been punitively posted to Mars after assaulting his commanding officer, who ordered his unit to fire upon civilians. The Martian space marine base acts as security for the Union Aerospace Corporation (UAC), a multi-planetary conglomerate, which is performing secret experiments with teleportation by creating gateways between the two moons of Mars, Phobos and Deimos. The manual makes it clear that Phobos is considered by space marines to be the dullest assignment imaginable: "with no action for fifty million miles, your day consisted of suckin' dust and watchin' restricted flicks in the rec room." This all changes when the UAC experiments go horribly wrong. Computer systems on Phobos malfunction, Deimos disappears entirely, and "something fragging evil" starts pouring out of the gateway, killing or possessing all UAC personnel. Responding to a frantic distress call from the overrun scientists, the Martian marine unit is quickly sent to Phobos to investigate, where the player character is left to guard the hangar with only a pistol while the rest of the group proceeds inside. Over the course of the next few hours, the marine hears assorted garbled radio messages, gunfire, and screams, followed by silence: "Seems your buddies are dead."

As the last man standing, the player character's mission is to fight through the entire onslaught of demonic enemies by himself in order to keep them from attacking Earth.^[6] In order for the game to be completed, the marine must fight through Phobos, Deimos, and then Hell itself, each presented as an episode containing eight distinct levels, along with an optional ninth hidden level for each one. Knee-Deep in the Dead, the first episode and the only one in the shareware version, is set in the high-tech military bases, power plants, computer centers and geological anomalies on Phobos. It ends with the player character entering the teleporter leading to Deimos, ending with him getting overwhelmed by monsters, if not killed. In the second episode, the Shores of Hell, the character journeys through the installations on Deimos, areas of which are interwoven with beastly architecture, warped and distorted by the hellish invasion. After defeating the titanic Cyberdemon lord, he discovers the truth about the vanished moon: it is floating above Hell. After climbing down to the surface, the third episode, called Inferno, begins. After the huge Spiderdemon that masterminded the invasion is destroyed in the final mission, a hidden doorway back to Earth opens for the hero, who has "proven too tough to be contained". In the game's final cutscene (PC version), the camera pans over a verdant field complete with flowers and bunny rabbits, only to reveal a burning city and a bunny's head impaled on a stake: the demons have invaded Earth, paving the way for Doom II.

The Ultimate Doom, the retail store version of the game, adds a fourth episode, Thy Flesh Consumed, occurring after the three original episodes of Doom and before Doom II. This episode was developed by independent master level designers with id's approval, and was designed for expert Doom players seeking a major challenge. It is considerably more difficult than the original three episodes.

Gameplay

Episode I: Knee-Deep in the Dead takes place in the facilities of the UAC and the military on Phobos

Yangshuo County, the scenery which provided the sky backdrop in Episode I.

Being a first-person shooter, Doom is experienced through the eyes of the main character. This character is not named throughout the game. The game's designer, John Romero, has pointed out that this is so the player feels more involved in the game: "There was never a name for the DOOM marine because it's supposed to be YOU."^[7] At its core, the gameplay is similar to classic shooter games (such as Space Invaders), presenting the player with the challenge of surviving while shooting every enemy in sight, but with its pseudo-3D first-person perspective giving environments a spatial representation that has a major effect on the level design and gameplay experience.^[8]

The objective of each level is simply to locate the exit room that leads to the next area, marked with an exit sign and/or a special kind of door, while surviving all hazards on the way. Among the obstacles are demonic monsters, pits of toxic or radioactive slime, ceilings that lower and crush the player character, and locked doors for which a keycard, skull-shaped key device, or remote switch must be located. The levels are sometimes labyrinthine and feature plenty of items such as additional ammo, health increases and other "power-ups" along the way, as well as the occasional secret areas which are not immediately obvious as a reward for players who explore more carefully. To ease navigation through the levels, a full screen automap is available and shows the areas explored to that point.

Doom is notable for the weapons arsenal available to the marine, which became prototypical for first-person shooters. The player character starts armed only with a pistol, and brass-knuckled fists in case the ammunition runs out, but larger weapons can be picked up: these are a chainsaw, a shotgun, a chaingun, a rocket launcher, a plasma rifle, and finally the immensely powerful BFG 9000. There is a wide array of power-ups, such as a backpack that increases the player character's ammunition-carrying capacity, armor, first aid kits to restore health, the berserk pack (a dark first aid box that puts the character into berserk mode, allowing him to deal out rocket launcher-level damage with his fists and potentially splattering former humans and imps, as well as setting the user's health to 100% if it was lower), supernatural blue orbs (named soul spheres in the manuals) that boost the player character's health up to a maximum of 200%, nightvision, computer maps (which show every area of the level), partial invisibility, and protective suits that allow the player to survive in toxic acids.

The enemy monsters in Doom make up the central gameplay element. The player character faces them in large numbers, with the number generally increased when the higher of the game's five difficulty levels is chosen when starting a new game. There are 10 types of monsters, including possessed humans as well as specifically hellish monsters, all which vary in many ways. The monsters have very simple behavior, consisting of either walking toward their opponent, or attacking by throwing fireballs, biting, and scratching. They will fight each other if one monster is accidentally harmed by another (though most monsters are not harmed by the ranged attacks of their own kind).

Many versions of Doom (and its sequels) include secret levels which are accessed by the player discovering alternate exits, often hidden behind secret doors or in areas which are difficult to reach. In some versions of Doom II both of these secret levels incorporate level design and characters from Doom's precursor, Wolfenstein 3D, which was also developed by id.

Aside from the single player game mode, Doom features two multiplayer modes playable over a network: "cooperative", in which two to four players team up, and "deathmatch", in which two to four players play against each other.

Development

Main article: Making of Doom

The development of Doom started in 1992, when John D. Carmack developed a new 3D game engine, the Doom engine, while the rest of the id Software team finished the Wolfenstein 3D prequel, Spear of Destiny. When the game design phase began in late 1992, the main thematic influences were the science fiction action film Aliens and the horror film Evil Dead II. The title of the game was picked by John Carmack:

There is a scene in The Color of Money where Tom Cruse shows up at a pool hall with a custom pool cue in a case. "What do you have in there?" asks someone. "Doom." replied Cruse with a cocky grin. That, and the resulting carnage, was how I viewed us springing the game on the industry.

— John Carmack^[9]

Designer Tom Hall wrote an elaborate design document called the Doom Bible, according to which the game would feature a detailed storyline, multiple player characters, and a number of interactive features.^[10] However, many of his ideas were discarded during development in favor of simpler design primarily advocated by John Carmack, resulting in Hall in the end being forced to resign due to not contributing effectively in the direction the rest of the team was going. Most of the level design that ended up in the final game is that of John Romero and Sandy Petersen. The graphics, by Adrian Carmack, Kevin Cloud and Gregor Punchatz, were modelled in various ways: although much was drawn or painted, several of the monsters were built from sculptures in clay or latex, and some of the weapons are toy guns from Toys "R" Us. A heavy metal-ambient soundtrack was supplied by Bobby Prince.^[11]

Engine technology

Main article: Doom engine

Doom's primary distinguishing feature at the time of its release was its realistic 3D graphics, then unparalleled by other real-time-rendered games running on consumer-level hardware. The advance from id Software's previous game Wolfenstein 3D was enabled by several new features in the Doom engine:

Doom relies heavily on contrasts of lighting in building its atmosphere.

• Height differences – all rooms in Wolfenstein 3D have the same height;
• Non-perpendicular walls – all walls in Wolfenstein 3D run along a rectangular grid;
• Full texture mapping of all surfaces – in Wolfenstein 3D, floors and ceilings are flat colors;
• Varying light levels and custom palettes – all areas in Wolfenstein 3D are fully lit at the same brightness. This contributed to Doom's visual authenticity, atmosphere and gameplay. The use of darkness to frighten or confuse the player was nearly unheard of in games released prior to Doom. Palette modifications were used to enhance effects such as berserk and invulnerability.

In contrast to the static levels of Wolfenstein 3D, those in Doom are highly dynamic: platforms can lower and rise, floors can rise sequentially to form staircases, and bridges can rise and fall. The lifelike environment was enhanced further by the stereo sound system, which made it possible to roughly determine the direction and distance of a sound effect. The player is kept on guard by the grunts and growls of monsters, and receives occasional clues to finding secret areas in the form of sounds of hidden doors opening remotely. As in Wolfenstein 3D, monsters can also become aware of the player's presence by hearing distant gunshots.

John Carmack had to make use of several tricks for these features to run smoothly on home computers of 1993. Most significantly, Doom levels are not truly three-dimensional; they are internally represented on a single plane, with height differences stored separately as displacements. (A similar trick is still used by many games to create huge outdoor environments.) This allows a two point perspective projection, with several design limitations: for example, it is not possible for the Doom engine to render one room over another. However, thanks to its two-dimensional property, the environment can be rendered very quickly, using a binary space partitioning method. Another benefit was the clarity of the automap, as that could be rendered with 2D vectors without any risk of overlapping. Additionally, the BSP tree technology created by Bruce Naylor was used.^[12]

Another important feature of the Doom engine is its modular data files, which allow most of the game's content to be replaced by loading custom WAD files. Wolfenstein 3D was not designed to be expandable, but fans had nevertheless figured out how to create their own levels for it, and Doom was designed to further extend the possibilities. The ability to create custom scenarios contributed significantly to the game's popularity (see the section on WADs, below).

Release and later history

Critical acclaim and popularity

The development of Doom was surrounded by much anticipation. The large number of posts in Internet newsgroups about Doom led to the SPISPOPD^[13] joke, to which a nod was given in the game in the form of a cheat code. In addition to news, rumors and screenshots, unauthorized leaked alpha versions also circulated online. (Many years later these alpha versions were sanctioned by id Software because of historical interest; they reveal how the game progressed from its early design stages.)^[14] The first public version of Doom was uploaded to Software Creations BBS and an FTP server at the University of Wisconsin–Madison on December 10, 1993.

Doom was released as shareware, with people encouraged to distribute it further. They did so: in 1995, Doom was estimated to have been installed on more than 10 million computers. Although most users did not purchase the registered version, over one million copies have been sold, and the popularity helped the sales of later games in the Doom series that were not released as shareware. In 1995, The Ultimate Doom (version 1.9, including episode IV) was released, making this the first time that Doom was sold commercially in stores.

To promote Windows 95, Bill Gates, aware of the video game's popularity, showcased a video presentation while digitally superimposed into Doom.

In a press release dated January 1, 1993, id Software had written that they expected Doom to be "the number one cause of decreased productivity in businesses around the world". This prediction came true at least in part: Doom became a major problem at workplaces, both occupying the time of employees and clogging computer networks with traffic caused by deathmatches. Intel, Lotus Development and Carnegie Mellon University are among many organizations reported to form policies specifically disallowing Doom-playing during work hours. At the Microsoft campus, Doom was by one account^[11] equal to a "religious phenomenon".

This cluttering of networks caused a package called Antidoom to be written: it ran on Novell networks, and if it detected a Doom game communication message, it sent to the sender a Doom game message which ended the game.

In late 1995, Doom was estimated to be installed on more computers worldwide than Microsoft's new operating system Windows 95, despite million-dollar advertising campaigns for the latter. The game's popularity prompted Bill Gates to briefly consider buying id Software,^[11] and led Microsoft to develop a Windows 95 port of Doom to promote the operating system as a gaming platform. One such presentation to promote Windows 95 had Bill Gates digitally superimposed into the game.^[15] The Microsoft 1995 release Excel 95 included a Doom-esque secret level as an Easter egg containing portraits of the programmers among other things. It is speculated that Microsoft engineers took advantage of their experience working on the Doom Windows 95 port to place the code in the spreadsheet program.^[16]

Doom was also widely praised in the gaming press. In 1994, it was awarded Game of the Year by both PC Gamer and Computer Gaming World. It also received the Award for Technical Excellence from PC Magazine, and the Best Action Adventure Game award by the Academy of Interactive Arts & Sciences.

In addition to the thrilling nature of the single-player game, the deathmatch mode was an important factor in the game's popularity. Doom was not the first first-person shooter with a deathmatch mode—MIDI Maze on the Atari ST had one in 1987, using the MIDI ports built into the ST to network up to four machines together. However, Doom was the first game to allow deathmatching over ethernet, and the combination of violence and gore with fighting friends made deathmatching in Doom particularly attractive. Two-player multiplayer was also possible over a phone line by using a modem, or by linking two PCs with a null-modem cable. Due to its widespread distribution, Doom hence became the game that introduced deathmatching to a large audience (and was also the first game to use the term "deathmatch").

WADs

Main article: Doom WAD

A Doom mod based on the Ghostbusters film.

The ability for others to create custom levels and otherwise modify the game, in the form of custom WAD files (short for Where is All the Data),^[17] turned out to be a particularly popular aspect of Doom. Gaining the first large mod-making community, Doom affected the culture surrounding first-person shooters, and also the industry. Several to-be 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.

The first level editors appeared in early 1994, and additional tools have been created that allow most aspects of the game to be edited. Although the majority of WADs contain one or several custom levels mostly in the style of the original game, others implement new monsters and other resources, and heavily alter the gameplay; several popular movies, television series, other video games and other brands from popular culture have been turned into Doom WADs by fans (without authorization), including Aliens, Star Wars, The X-Files, The Simpsons, South Park, Sailor Moon, Dragon Ball Z, Red Faction, Pokémon and Batman. Some works, like the Theme Doom Patch, combined enemies from several films, such as Aliens, Predator and The Terminator.

Some add-on files were also made that changed the sounds made by the various characters and weapons. Notable ones were samples from Beavis and Butthead and the famous faked orgasm scene from When Harry Met Sally....

Around 1994 and 1995, WADs were primarily distributed online over bulletin board systems or sold in collections on compact discs in computer shops, sometimes bundled with editing guide books. FTP servers became the primary method in later years. A few WADs have been released commercially, including the Master Levels for Doom II, which was released in 1995 along with Maximum Doom, a CD containing 1,830 WADs that had been downloaded from the Internet. Several thousand WADs have been created in total: the idgames FTP archive contains over 13,000 files,^[18] and this represents only a fraction of the complete output of Doom fans.

Third party programs were also written to handle the loading of various WADs, since the game is a DOS game and all commands had to be entered on the command line to run. A typical launcher would allow the player to select which files to load from a menu, making it much easier to start.

WizardWorks Software released the D!Zone expansion pack featuring hundreds of levels for Doom and Doom II.^[19] D!Zone was reviewed in Dragon by Jay & Dee; Jay gave the pack 1 out of 5 stars, while Dee gave the pack 1½ stars.^[19]

Clones and related products

Main articles: First-person shooter, Versions and ports of Doom, and Doom spin-offs and homages

The phrase "Doom clone" was initially popular to describe the style of gameplay in Doom-like games, but after 1996 was gradually replaced by "first-person shooter" By 1998 the phrase "first-person shooter" had firmly superseded "Doom clone"

The popularity of Doom led to the development of a sequel, Doom II: Hell on Earth (1994), as well as expansion packs and alternate versions based on the same game engine, including The Ultimate Doom (1995), Final Doom (1996), and Doom 64 (1997). Doom became a "killer app" that all capable consoles and operating systems were expected to have, and versions of Doom have subsequently been released for the following systems: DOS, Microsoft Windows, Linux, Apple Macintosh, Super NES, Sega 32X, Sony PlayStation, Game Boy Advance, iOS, Symbian OS, RISC OS, Atari Jaguar, Sega Saturn, Nintendo 64, Tapwave Zodiac, 3DO, Xbox, and Xbox Live Arcade. The total number of copies of Doom games sold is unknown, but may be well over 4 million; Doom II alone has earned over $100 million in total sales.

The game engine was licensed to several other companies as well, who released their own games based on it, including Heretic, Hexen, Strife and HacX. A Doom-based game called Chex Quest was released in 1996 by Ralston Foods as a promotion to increase cereal sales,^[20] and the United States Marine Corps released Marine Doom, designed to "teach teamwork, coordination and decision-making".

Dozens of new first-person shooter titles appeared following Doom's release, and they were often referred to as Doom "clones" rather than "first-person shooters". Some of these were certainly "clones"—hastily assembled and quickly forgotten—others explored new grounds of the genre and were highly acclaimed. Many of the games closely imitated features in Doom such as the selection of weapons and cheat codes. Doom's principal rivals were Apogee's Rise of the Triad and Looking Glass Studios' System Shock. The popularity of Star Wars-themed WADs is rumored to have been the factor that prompted LucasArts to create their first-person shooter Dark Forces.^[21]

When, three years later, 3D Realms released Duke Nukem 3D, a tongue-in-cheek science fiction shooter based on Ken Silverman's technologically similar Build engine, id Software had nearly finished Quake, its next-generation game, which mirrored Doom's success for the remainder of the 1990s and significantly reduced interest in its predecessor. The franchise remained in that state until 2000, when Doom 3 was announced. A retelling of the original Doom using entirely new graphics technology, Doom 3 was hyped to provide as large a leap in realism and interactivity as the original Doom, and helped renew interest in the Doom franchise when it was released.

Doom has appeared in several forms in addition to games, including a comic book, four novels by Dafydd Ab Hugh and Brad Linaweaver (loosely based on events and locations in the games), a board game and even a live-action film starring Karl Urban and The Rock released in 2005. The game's development and impact on popular culture is also the subject of the book Masters of Doom by David Kushner.

Controversies

Doom's level of graphic violence made the game highly controversial

Doom is notorious for its high levels of violence, gore, and satanic imagery, which have generated much controversy from a broad range of groups. Yahoo! Games has it listed as one of the top ten most controversial games of all time.^[22] It has been criticized numerous times by religious organizations for its diabolic undertones and was dubbed a "mass murder simulator" by critic and Killology Research Group founder David Grossman.^[23] Doom prompted fears that the then-emerging virtual reality technology could be used to simulate extremely realistic killing.

The game again sparked controversy throughout a period of school shootings in the United States when it was found that Eric Harris and Dylan Klebold, who committed the Columbine High School massacre in 1999, were avid players of the game. While planning for the massacre, Harris said that the killing would be "like fucking Doom", and "it'll be like the LA riots, the Oklahoma bombing, WWII, Vietnam, Duke Nuke 'Em and Doom all mixed together", and that his shotgun was "straight out of the game".^[24] A rumor spread afterwards that Harris had designed Doom levels that looked like the halls of the high school, populated with representations of Harris's classmates and teachers, and that Harris practiced for his role in the shootings by playing these levels over and over. Although Harris did design Doom levels, they were not simulations of Columbine High School.^[25]

While Doom and other violent video games have been blamed for nationally covered school shootings, recent research featured by Greater Good Science Center^[26] shows that the two are not closely related. Harvard medical school researchers Cheryl Olson and Lawrence Kutner found that violent video games did not correlate to school shootings. The U.S. Secret Service and Department of Education analyzed 37 incidents of school violence and sought to develop a profile of school shooters, they discovered that the most common traits among shooters were that they were male and had histories of depression and attempted suicide. While many of the killers—like the vast majority of young males—did play video games, this study did not find a relationship between game play and school shootings. In fact, only one eighth of the shooters showed any special interest in violent video games; far less than the number of shooters who seemed attracted to books and movies with violent content.^[27]

Legacy

Doom is widely regarded as one of the most important titles in gaming history. It was voted the #1 game of all time in a poll among over 100 game developers and journalists conducted by GameSpy in July 2001,^[28] and PC Gamer proclaimed Doom the most influential game of all time in its ten-year anniversary issue in April 2004, and named it the second best game of all time a year later (number one was Half-Life). GameTrailers ranked Doom as #1 "Breakthrough PC Game".^[29] In 2009, Game Informer put Doom 6th on their list of "The Top 200 Games of All Time", saying that it "[gave] the genre the kick start it needed to rule the gaming landscape two decades later".^[30]

Although the popularity of the Doom games dropped with the release of more modern first-person shooters, the game had still retained a strong fan base that continues to this day by playing competitively and creating WADs (the idgames FTP archive receives a few to a dozen new WADs each week as of 2005^[update]), and Doom-related news is still tracked at multiple websites such as Doomworld. Interest in Doom was renewed in 1997, when the source code for the Doom engine was released (it was also placed under the GNU General Public License in 1999). Fans then began porting the game to various operating systems, even to previously unsupported platforms such as the Dreamcast. As for the PC, there have been additions of new features such as OpenGL rendering and scripting, which allow WADs to alter the gameplay more radically. There are well over 50 different Doom source ports, some of which remain under active development.

Devoted players have spent years creating speedruns for Doom, competing for the quickest completion times and sharing knowledge about routes through the levels and how to exploit bugs in the Doom engine for shortcuts. Achievements include the completion of both Doom and Doom II on the Ultra-Violence difficulty setting in less than 30 minutes each. In addition, a few players have also managed to complete Doom II in a single run on the Nightmare! difficulty setting, on which monsters are more aggressive, launch faster projectiles (or, in the case of the Pinky Demon, simply move faster), and respawn roughly 30 seconds after they have been killed (level designer John Romero characterized the idea of such a run as "[just having to be] impossible").^[31] Movies of most of these runs are available from the COMPET-N website.

Online co-op and deathmatch play still continues on servers listed through services such as Odamex,^[32] Skulltag,^[33] ZDaemon^[34] and Doom Connector.^[35] Some of the source ports used for online play (for example Skulltag) also support additional game modes such as "last man standing", "survival" (co-op) and "invasion" modes.

References

1. ^ The Ultimate Doom system requirements, on id Software official site
2. ^ id Software (1993). "Doom Press Release". http://www.rome.ro/lee_killough/history/doompr3.shtml. Retrieved April 2, 2008. 
3. ^ Entertainment Software Rating Board. "Game ratings". http://www.esrb.org/search_results.asp?key=doom&x=0&y=0&type=game. Retrieved December 4, 2004. 
4. ^ "Top 50 Games of All Time". Gamespy. http://archive.gamespy.com/articles/july01/top501aspe/index4.shtm. Retrieved April 24, 2006. 
5. ^ "Legendary id Software games now on Steam". Steam. August 3, 2007. http://store.steampowered.com/news/1141/. Retrieved July 27, 2011. 
6. ^ id Software (1993). "The Doom story (unofficial transcript)". http://www.btinternet.com/~ianohare/Doomstory.htm. Retrieved February 25, 2008. 
7. ^ Romero, John (2002). "Doom Marine's Name forum post at Planet Romero". http://rome.ro/smf/index.php/topic,1521.msg31827.html#msg31827. Retrieved August 23, 2008. 
8. ^ Mäyrä, Frans (2008), An Introduction to Games Studies: Games in Culture, SAGE, p. 104, ISBN 1412934451, http://books.google.co.uk/books?id=iI0kAQAAIAAJ, retrieved April 10, 2011, "The gameplay of Doom is at its core familiar from the early classics like Space Invaders ... it presents the player with the clear and simple challenge of surviving while shooting everything that moves." 
9. ^ Doomworld. "Interview with John Carmack". http://doomworld.com/interviews/int7.shtml. Retrieved November 15, 2005. 
10. ^ Hall, Tom (1992). "The Doom Bible". Doomworld (1998). http://5years.doomworld.com/doombible/. Retrieved November 15, 2005. 
11. ^ ^{a b c} Kushner, David (2003). Masters of Doom: How Two Guys Created an Empire and Transformed Pop Culture. Random House Publishing Group. ISBN 0-375-50524-5. 
12. ^ "In the Chain with ... John Romero", Retro Gamer magazine, issue 75, pp. 78–89.
13. ^ SPISPOPD = Smashing Pumpkins Into Small Piles Of Putrid Debris Seth Cohn's S.P.I.S.P.O.P.D.
14. ^ "Doom Alphas and Betas". Nathan's Toasty Technology page. http://toastytech.com/dooma/index.html. Retrieved July 27, 2011. 
15. ^ Lombardo, Mike. "Bonus movie: Bill Gates "DOOM" video". Reel Splatter. http://www.reelsplatter.com/doommedia.html. Retrieved November 15, 2005. 
16. ^ "Excel Easter Egg - Excel 95 Hall of Tortured Souls". The Easter Egg Archive. July 19, 1999. http://www.eeggs.com/items/719.html. Retrieved July 27, 2011. 
17. ^ "Doom Bible Appendices". http://5years.doomworld.com/doombible/appendices.shtml. Retrieved April 20, 2010. 
18. ^ Doomworld. "/idgames database". http://www.doomworld.com/idgames/. Retrieved September 3, 2005. 
19. ^ ^{a b} Jay & Dee (May 1995). "Eye of the Monitor". Dragon (217): 65–74. 
20. ^ House, Michael L.. "Chex Quest - Overview". allgame. http://www.allgame.com/game.php?id=14300&tab=overview. Retrieved July 27, 2011. 
21. ^ Turner, Benjamin & Bowen, Kevin (2003). "Bringin' in the DOOM Clones". GameSpy. http://archive.gamespy.com/articles/december03/doom/clones/index2.shtml. Retrieved November 15, 2005. 
22. ^ Ben Silverman (September 17, 2007). "Controversial Games". Yahoo! Games. http://videogames.yahoo.com/feature/controversial-games/530593. Retrieved September 19, 2007. 
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External links

Official website

• Ultimate Doom at id Software

Information resources

• 1993: DOOM – John Romero's Doom page
• Doom (VG) at the Internet Movie Database
• Doom on Doom Wiki
• Classic Doom Online - online multiplayer set up instructions
• Leukart, Hank (1994). "The "Official" Doom FAQ". http://www.gamers.org/docs/FAQ/doomfaq/. Retrieved November 15, 2005.