Doom (1993 video game)
Doom is a first-person shooter game developed and self-published by id Software. Released on December 10, 1993, for DOS, it is the first installment in the Doom franchise. The player assumes the role of a space marine, popularly known as the Doomguy, fighting through hordes of undead humans and invading demons. The game begins on the moons of Mars and finishes in hell, with the player traversing each level to find its exit or defeat its final boss.
Doom was the third major independent release by id Software, after Commander Keen (1990–1991) and Wolfenstein 3D (1992). In May 1992, id started developing a game focused on fighting demons with technology, made using a new 3D game engine from developer John Carmack, with a darker style than their previous titles. Designer Tom Hall initially wrote a science fiction plot, but he and his work were removed from the project, with the final game featuring an action-heavy design from John Romero and Sandy Petersen. The game was self-published by id as a set of three episodes under the shareware model, marketing the full game by releasing the first episode for free. A retail version with an additional episode was published in 1995 by GT Interactive as The Ultimate Doom.
Doom was a critical and commercial success upon release, earning a reputation as one of the best and most influential games of all time. It sold an estimated 3.5 million copies by 1999, and up to 20 million people are estimated to have played it within two years of launch. It has been termed the "father" of the first-person shooter genre and is regarded as one of the most important games in the genre. It led to an array of imitators and clones, as well as a robust modding scene, and the birth of speedrunning as a community. Doom has been ported to a wide variety of platforms both officially and unofficially ever since and has been followed by several games in the series, including Doom II (1994), Doom 3 (2004), Doom (2016), and Doom Eternal (2020), as well as the films Doom (2005) and Doom: Annihilation (2019).

Gameplay
Doom is a first-person shooter presented with 3D graphics. In the single-player campaign mode, the player controls an unnamed space marine—later termed "Doomguy"—through military bases on the moons of Mars and in hell. To finish a level, the player must traverse through labyrinthine areas to reach a marked exit room. Levels are grouped into named episodes, with the final level of each focusing on a boss fight. While the environment is presented in a 3D perspective, the enemies and objects are instead 2D sprites rendered at fixed 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. 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 simple behavior, consisting of either moving toward their opponent if they see or hear the player or attacking by biting, clawing, or using magic abilities such as fireballs. They will reactively fight each other if one monster inadvertently harms another, though most monsters are immune to attacks of their kind.The player must manage supplies of ammunition, health, and armor while traversing the levels. 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. The player also encounters pits of toxic waste, ceilings that lower and crush objects, and locked doors requiring a collectable keycard or a remote switch. 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 allow the player to unlock all weapons, walk through walls, or become invulnerable.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, each containing about nine levels: "Knee-Deep in the Dead", "The Shores of Hell", and "Inferno". A fourth episode, "Thy Flesh Consumed", was added in an expanded version, The Ultimate Doom, released two years after Doom. The campaign contains very few plot elements, with a minimal story presented mostly through the instruction manual and text descriptions between episodes.
In the future, an unnamed marine 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 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 facilities on Phobos. The episode ends with the marine defeating two powerful Barons of Hell guarding a teleporter to the Deimos base. After the battle, the marine emerges from the teleporter and is knocked unconscious by a horde of enemies, awakening with only a pistol. In "The Shores of Hell", the marine fights through corrupted research facilities on Deimos, culminating in the defeat of 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 battles through hell itself and destroys a cybernetic spider-demon that masterminded the invasion of the moons. When a portal to Earth opens, the marine steps through to discover that Earth has been invaded. "Thy Flesh Consumed" follows the marine's initial assault on the Earth invaders, setting the stage for Doom II.

Development
Concept
Id Software released Wolfenstein 3D in May 1992. Later called the "grandfather of 3D shooters", the game established the genre's popularity and its reputation for fast action and technological advancement. When most of the studio began work on additional episodes for Wolfenstein, id co-founder and lead programmer John Carmack instead began technical research on a new game. Following the release of Wolfenstein 3D: Spear of Destiny in September 1992, the team began to plan their next game. They were largely tired of Wolfenstein and wanted to create another 3D game using a new engine Carmack was developing. Co-founder and lead designer Tom Hall proposed a new game in the Commander Keen series, but the team ultimately decided that the platforming gameplay of the series was a poor fit for Carmack's fast-paced 3D engines. Additionally, the other two co-founders of id, designer John Romero and lead artist Adrian Carmack, wanted to create something in a darker style than the Keen games. John Carmack then came up with another concept: a game about using technology to fight demons, inspired by the Dungeons & Dragons campaigns the team played, combining the styles of Evil Dead II and Aliens. The project's working title was Green and Pissed, but Carmack renamed it Doom based on a line from the 1986 film The Color of Money: "'What you got in there?' / 'In here? Doom.'"The team agreed to pursue the Doom concept, and development began in November 1992. The initial development team was composed of five people: programmers John Carmack and Romero, artists Adrian Carmack and Kevin Cloud, and designer Hall. They moved operations to a dark office building, naming it "Suite 666" while drawing inspiration from the noises they heard from a neighboring dental practice. They also decided to cut ties with Apogee Software, their previous publisher, and self-publish Doom.

Design
Early in development, rifts in the team began to appear. In November, Hall delivered a design document that he called the "Doom Bible", detailing the project's plot, backstory, and design goals. His design was a science fiction horror concept wherein scientists on the Moon open a portal to an alien invasion. Over a series of levels, the player discovers that the aliens are demons while hell steadily infects the level design. John Carmack not only disliked the proposed story but dismissed the idea of having a story at all: "Story in a game is like story in a porn movie; it's expected to be there, but it's not that important." Rather than a deep story, he wanted to focus on technological innovation, dropping the levels and episodes of Wolfenstein in favor of a fast, continuous world. Hall disliked the idea, but the rest of the team sided with Carmack. Hall spent the next few weeks reworking the Doom Bible to work with Carmack's technological ideas. However, the team then realized that Carmack's vision for a seamless world would be impossible given the hardware limitations, and Hall was forced to rework the design document once again.At the start of 1993, id put out a press release, touting Hall's story about fighting off demons while "knee-deep in the dead". The press release proclaimed the new 3D engine features that John Carmack had created, as well as other aspects of the game, including multiplayer, that had not yet even been designed. Early versions were built to match the Doom Bible; a "pre-alpha" version of the first level included Hall's introductory base scene. Initial versions also retained Wolfenstein's arcade-style scoring, but this was quickly removed as it clashed with Doom's intended tone. The studio also experimented with other game systems before removing them, such as lives, an inventory, a secondary shield, and a complex user interface.Soon, however, the Doom Bible as a whole was rejected. Romero wanted a game even "more brutal and fast" than Wolfenstein, which did not leave room for the character-driven plot Hall had created. Additionally, the team believed it emphasized realism over entertaining gameplay, and they did not see the need for a design document at all. Some ideas were retained, but the story was dropped and most of the design was removed. By early 1993, Hall created levels that became part of an internal demo. Carmack and Romero, however, rejected the military architecture of Hall's level design. Romero especially believed that the boxy, flat level designs failed to innovate on Wolfenstein, and failed to show off the engine's capabilities. He began to create his own, more abstract levels, which the rest of the team saw as a great improvement.Hall was upset with the reception of his designs and how little impact he was having as the lead designer. He was also upset with how much he was having to fight with John Carmack to get what he saw as obvious gameplay improvements, such as flying enemies, and began to spend less time at work. In July the other founders of id fired Hall, who went to work for Apogee. He was replaced by Sandy Petersen in September, ten weeks before the game was released. Petersen later recalled that John Carmack and Romero wanted to hire other artists instead, but Cloud and Adrian disagreed, saying that a designer was required to help build a cohesive gameplay experience. The team also added a third programmer, Dave Taylor.Petersen and Romero designed the rest of Doom's levels, with different aims: the team believed that Petersen's designs were more technically interesting and varied, while Romero's were more aesthetically interesting. In late 1993, after the multiplayer component was coded, the development team began playing four-player games, which Romero termed "deathmatch". According to Romero, the deathmatch mode was inspired by fighting games such as Street Fighter II, Fatal Fury, and Art of Fighting.

Engine
Doom was written largely in the C programming language, with a few elements in assembly language. The developers used NeXT computers running the NeXTSTEP operating system. The level and graphical data was stored in WAD files, short for "Where's All the Data?", separately from the engine. This allowed for any part of the design to be changed without needing to adjust the engine code. Carmack designed this system so that fans could easily modify the game; he had been impressed by the modifications made by fans of Wolfenstein 3D and wanted to support that by releasing a map editor with an easily swappable file structure.Unlike Wolfenstein, which has flat levels with walls at right angles, the Doom engine allows for walls and floors at any angle or height but does not allow areas to be stacked vertically. The lighting system is based on adjusting the color palette of surfaces directly. Rather than calculating how light traveled from light sources to surfaces using ray tracing, the game calculates the "light level" of a small area based on the predetermined brightness of said area. It then modifies the color palette of that section's surface textures to mimic how dark it would look. This same system is used to cause far away surfaces to look darker than close ones.Romero came up with new ways to use Carmack's lighting engine, such as strobe lights. He programmed engine features such as switches and movable stairs and platforms. After Romero's complex level designs started to cause problems with the engine, Carmack began to use binary space partitioning to quickly select the reduced portion of a level that the player could see at a given time. Taylor, along with programming other features, added cheat codes.

Art direction
Adrian Carmack was the lead artist for Doom, with Kevin Cloud as an additional artist. They designed the monsters to be "nightmarish", with graphics that were realistic and dark instead of staged or rendered. A mixed media approach was taken to create them. The artists sculpted models of some of the enemies and took pictures of them in stop motion from five to eight different angles so that they could be rotated realistically in-game. The images were then digitized and converted to 2D characters with a program written by John Carmack. Adrian Carmack made clay models for a few demons and had Gregor Punchatz build latex and metal sculptures of the others. The weapons were made from combined parts of children's toys. The developers scanned themselves as well, using Cloud's arm for the marine's arm holding a gun, and Adrian's snakeskin boots and wounded knee for textures.As with Wolfenstein 3D, id hired composer Bobby Prince to create the music and sound effects. Romero directed Prince to make the music in techno and metal styles. Many tracks were directly inspired by songs by metal bands such as Alice in Chains and Pantera. Prince believed that ambient music would be more appropriate and produced numerous tracks in both styles in hope of convincing the team, and Romero incorporated both. Prince did not make music for specific levels, as they were composed before the levels were completed; instead, Romero assigned each track to each level late in development. Prince created the sound effects based on short descriptions or concept art of a monster or weapon and adjusted them to match the completed animations. The monster sounds were created from animal noises, and Prince designed all the sounds to be distinct on the limited sound hardware of the time, even when many sounds were playing at once. He also designed the sound effects to play on different frequencies from those used for the MIDI music, so they would clearly cut through the music.

Release
Id Software planned to self-publish the game and set up a distribution system leading up to the release. Jay Wilbur, who had been hired as CEO and sole member of the business team, planned the marketing and distribution of Doom. As id would make the most money from copies they sold directly to customers—up to 85% of the planned US$40 price—he decided to leverage the shareware market as much as possible. He believed that the mainstream press was uninterested in the game and bought only a single ad in any gaming magazine. Instead, he gave software retailers the option to sell copies of the first Doom episode at any price, in hopes of motivating customers to buy the full game directly from id.The team planned to release Doom in the third quarter of 1993 but ultimately needed more time. By December 1993, the team was working non-stop, with several employees sleeping at the office. Taylor said that working on the game gave him such a rush that he would pass out from the intensity. id began receiving calls from people interested in the game or angry that it had missed its planned release date, as anticipation had been building on the nascent internet. At midnight on December 10, 1993, after working for 30 straight hours, the development team at id uploaded the first episode to the internet, letting interested players distribute it for them. The team was unable to connect to the FTP server at the University of Wisconsin–Madison where they planned to upload the game, since there were so many users already connected in anticipation of the release. The network administrator was forced to kick them off to make room. When the upload finished 30 minutes later, 10,000 people attempted to download the game at once, crashing the university's network.Within hours of Doom's release, university networks began banning Doom multiplayer games, as a rush of players overwhelmed their systems. The morning after release, John Carmack quickly released a patch in response to complaints of network congestion from administrators, who still needed to implement Doom-specific rules to keep their networks from crashing from the load. In 1995, id created an expanded version of Doom for the retail market with a fourth episode of levels, which was published by GT Interactive as The Ultimate Doom.

Ports
Doom has been ported to numerous different platforms, independent from id Software. The first port of Doom was an unofficial port to Linux, released by id programmer Dave Taylor in 1994; it was hosted by id but not supported or made official. Microsoft attempted to hire id to port Doom to Windows in 1995 to promote Windows as a gaming platform, and Microsoft CEO Bill Gates briefly considered buying the company. When id declined, Microsoft made its own port, with a team lead by Gabe Newell. One promotional video for Windows 95 had Gates digitally superimposed into the game.Other official ports of Doom were released for the Sega 32X, Atari Jaguar, and Mac OS in 1994, SNES and PlayStation in 1995, 3DO in 1996, Sega Saturn in 1997, Acorn Risc PC in 1998, Game Boy Advance in 2001, Xbox 360 in 2006, iOS in 2009, and Nintendo Switch, Xbox One, PlayStation 4, and Android in 2019. Some of these became bestsellers even many years after the initial release. The source code for Doom was released under a non-commercial license in 1997, and freely released under the GNU General Public License in 1999. Doom has been ported unofficially to numerous platforms due to the release of the source code; so many ports exist, including for esoteric devices such as smart thermostats and oscilloscopes, that variations on "It runs Doom" or "Can it run Doom?" are long-running memes.

Reception
Sales
Upon its release in December 1993, Doom became an "overnight phenomenon". It was an immediate financial success for id, making a profit within a day after release. Although the company estimated that only one percent of shareware downloaders bought the full game, this was enough to generate daily revenue of US$100,000, selling in one day what Wolfenstein sold in one month. Sandy Petersen said that Doom sold around 200,000 copies in its first year, and in 1995 Wilbur estimated the first-year sales as 140,000.By late 1995, Doom was estimated to be installed on more computers worldwide than Microsoft's new operating system, Windows 95. According to PC Data, by April 1998 Doom's shareware edition had yielded 1.36 million units sold and US$8.74 million in revenue in the United States. This led PC Data to declare it the country's fourth-best-selling computer game since 1993. The Ultimate Doom sold over 780,000 units by September 1999, and all versions of the game combined sold 3.5 million copies by the end of 1999. In addition to sales, an estimated six million people played the shareware version by 2002; other sources estimated in 2000 that 10–20 million people played Doom within 24 months of its launch.

Reviews
Doom was highly praised in contemporaneous reviews. In April 1994, a few months after release, PC Gamer UK named it the third-best computer game of all time, claiming "Doom has already done more to establish the PC's arcade clout than any other title in gaming history," and PC Gamer US named it the best computer game of all time that August. Computer Gaming World and PC Gamer UK named Doom Game of the Year that same year.Reviewers praised the single-player gameplay, though some felt it was lacking in depth. Electronic Entertainment called it "a skull-banging, palm-sweating, blood-pounding game", while The Age said it was "a technically superb and thrilling 3D adventure". PC Zone called it the best arcade game ever. Computer Gaming World concluded that it was "a virtuoso performance". Dragon said it was a "terrific showcase" of fast gameplay, but that overall it "lacks a certain depth"; Computer and Video Games similarly found it "riveting", but repetitive. Edge, in a lower-scored review, disliked the lack of variety in gameplay, infamously ending its review with "If only you could talk to these creatures, then perhaps you could try and make friends with them, form alliances... Now, that would be interesting," which became a running joke in video game culture. The multiplayer gameplay was universally applauded. Computer Gaming World called it "the most intense gaming experience available"; Dragon similarly called it "the biggest adrenaline rush available on computers". PC Zone named it as the best multiplayer game available, in addition to the best arcade game.The 3D graphics and art style were praised by reviewers; Computer Gaming World called the graphics "simply dazzling", while Edge said that it "made serious advances in what people will expect of 3D graphics in future", surpassing not only prior games but games that had yet to be released. Compute! and Electronic Games similarly called the graphics excellent and unlike any other game's. PC Zone, Dragon, Computer Gaming World, and Electronic Entertainment all praised the atmosphere and art direction, saying that the level design, lighting effects, and sound effects combined to create a "claustrophobic" and "nightmarish experience". Computer Gaming World also praised the music, as did the The Mercury News, which called it as "ominous as the scenario".

Other versions
The Ultimate Doom received mixed reviews upon its release in 1995, as in the review from PC Zone, which gave it a score of 90/100 for new players but 20/100 for anyone who had the original game. They viewed it as solely a level pack due to the lack of new features and compared it negatively to the hundreds of free fan-made levels available on the internet. Joystick similarly disliked the limited amount of additional content and recommended it only to major fans or those who had not played the game. Fusion reviewed the edition positively, praising the difficulty of the new levels, as did GameSpot, which considered it in the sense of introducing the game to new players.The first ports of Doom received comparable reviews to the original PC version. VideoGames, GamePro, and Computer and Video Games all gave the Jaguar version high scores, comparing it favorably with the PC version. GamePro and Computer and Video Games also rated the Sega 32X version highly, though they noted that the graphics were worse and the game shorter than the PC or Jaguar versions. The 1995 ports received mixed reviews. The PlayStation version was rated highly by HobbyConsolas, GamePro, and Maximum, which applauded the inclusion of Doom II and extra levels, and favorably compared it to other PlayStation shooter games. The SNES version, however, was noted for weaker graphics and unresponsive controls, though reviewers such as Computer and Video Games, GamePro, and Next Generation were split on giving the game high or middling scores due to these faults. Later 1990s ports received worse reviews; the 3DO port was panned by GamePro and Maximum for having worse graphics, a smaller screen size, and less intelligent enemies than any previous version, and the Sega Saturn port also met with low reviews for poor graphics and low quality from Mean Machines and Sega Saturn Magazine.

Legacy
Doom has been termed "inarguably the most important" first-person shooter, as well as the "father" of the genre. Although not the first in the genre, it was the game with the greatest impact. It has additionally been named as one of the most influential games in any genre, such as by PC Gamer, which proclaimed Doom the most influential game of all time in 2004. It also popularized the business model of online distribution. In 2007 Doom was listed among the ten "game canon" video games selected for preservation by the Library of Congress. In 2015, The Strong National Museum of Play inducted Doom to its World Video Game Hall of Fame as part of its initial set of games.Doom has continued to be included highly in lists of the best video games ever for nearly three decades since its release. In 1995, Next Generation said it was "the most talked about PC game ever". The PC version was ranked the 3rd best video game by Flux in 1995, and in 1996 was ranked fifth best and third most innovative by Computer Gaming World. In 2000, Doom was ranked as the second-best game ever by GameSpot. The following year, it was voted the number one game of all time in a poll among over 100 game developers and journalists conducted by GameSpy, and was ranked the sixth best game by Game Informer. GameTrailers ranked it the most "breakthrough PC game" in 2009 and Game Informer again ranked it the sixth-best game that same year. Doom has also been ranked among the best games of all time by GamesMaster, Hyper, The Independent, Entertainment Weekly, GamesTM, Jeuxvideo.com, Gamereactor, Time, Polygon, and The Times, among others, as recently as 2023.

Clones
The success of Doom led to dozens of new first-person shooter games. In 1998, PC Gamer declared it "probably the most imitated game of all time". These games were often referred to as "Doom clones", with "first-person shooter" only overtaking it as the name of the genre after a few years.Doom clones ranged from close imitators to more innovative takes on the genre. Id Software licensed the Doom engine to several other companies, which resulted in several games similar to Doom, including Heretic (1994), Hexen: Beyond Heretic (1995), and Strife: Quest for the Sigil (1996). A Doom-based game called Chex Quest was released in 1996 by Ralston Foods as a promotion to increase cereal sales. Other games were inspired by Doom, if not rumored to be built by reverse engineering the game's engine, including LucasArts's Star Wars: Dark Forces (1995). Several other games termed Doom clones, such as PowerSlave (1996) and Duke Nukem 3D (1996), used the 1995 Build engine, a 2.5D engine inspired by Doom created by Ken Silverman with some consultation with John Carmack.

Sequel and franchise
After completing Doom, id Software began working on a sequel using the same engine, Doom II, which was released as a retail title on October 10, 1994, ten months after the first game. GT Interactive had approached id before the release of Doom with plans to release a retail version of Doom and Doom II. Id chose to create the sequel as a set of episodes rather than a new game, allowing John Carmack and the other programmers to begin work on id's next game, Quake. Doom II was the United States' highest-selling software product of 1994 and sold more than 1.2 million copies within a year.Doom II was followed by an expansion pack from id, Master Levels for Doom II (1995), consisting of 21 commissioned levels and over 3000 user-created levels for Doom and Doom II. Two sets of Doom II levels by different amateur map-making teams were released together by id as the standalone title Final Doom (1996). Doom and Doom II were both included, along with previous id games, in the id Anthology compilation (1996). The Doom franchise has continued since the 1990s in several iterations and forms. The video game series includes Doom 3 (2007), Doom (2016), and Doom Eternal (2020), along with other spin-off video games. It additionally includes multiple novels, a comic book, board games, and two films: Doom (2005) and Doom: Annihilation (2019).

Controversies
Doom was notorious for its high levels of graphic violence and satanic imagery, which generated controversy from a broad range of groups. Doom for the Sega 32X was one of the first video games to be given a Mature 17+ rating from the Entertainment Software Rating Board due to its violent gore and nature, while Doom II was the first. Doom was banned from sale in Germany due to its violence, and this was only rescinded in 2011.Doom again sparked controversy in the United States when it was found that Eric Harris and Dylan Klebold, who committed the Columbine High School massacre on April 20, 1999, were avid players. While planning for the massacre, Harris said in his journal that the killing would be "like playing Doom". A rumor spread afterward that Harris had designed a custom Doom level that looked like the high school, populated with representations of Harris's classmates and teachers, which he used to practice for the shooting. The game was dubbed a "mass murder simulator" by critic and Killology Research Group founder David Grossman. Although Harris did design several custom Doom levels, which later became known as the "Harris levels", none were based on the school.In the earliest release versions, the level E1M4: Command Control contains a swastika-shaped structure, which was put in as a homage to Wolfenstein 3D. The swastika was removed in later versions, out of respect for a military veteran's request, according to Romero.

Community
Doom's popularity and innovations attracted a community that has persisted for decades since. The deathmatch mode was an important factor in the game's popularity. Doom was the first game to coin the term "deathmatch" and introduced multiplayer shooting battles to a wide audience. This led to a widespread community of players who had never experienced fast-paced multiplayer combat before.Another popular aspect of Doom was the versatility of its WAD files, enabling user-generated levels and other game modifications. John Carmack and Romero had strongly advocated for mod support, overriding other id employees who were concerned about commercial and legal implications. Although WAD files exposed the game data, id provided no instructions for how they worked. Still, players were able to modify leaked alpha versions of the game, allowing them to release level editors within weeks of the game's release.On January 26, 1994, university student Brendon Wyber led a group to create the first full level editor, the Doom Editor Utility, leading to the first custom level by Jeff Bird in March. It was followed by "countless" others, including many based on other franchises like Aliens and Star Wars total conversion mods, as well as DeHackEd, a level editor first released in 1994 by Greg Lewis that allowed editing of the game engine. Soon after the first mods appeared, id CEO Wilbur posted legal terms to the company's website, allowing mod authors to charge money without any fees to id, while also absolving the company of responsibility or support.Doom mods were widely popular, earning favorable comparisons to the official level additions seen in The Ultimate Doom. Thousands of user-created levels were released in the first few years after the release; over 3000 such levels for Doom and Doom II were included in the official retail release Master Levels for Doom II (1995). WizardWorks released multiple collections of mods of Doom and Doom II under the name D!Zone. At least one mod creator, Tim Willits, was later hired at id Software. Mods have continued to be produced, with the community Cacowards awarding the best of each year. In 2016, Romero created two new Doom levels: E1M4b ("Phobos Mission Control") and E1M8b ("Tech Gone Bad"). In 2018, for the 25th anniversary of Doom, Romero announced Sigil, an unofficial fifth episode containing nine levels. It was released on May 22, 2019, for €6.66 with a soundtrack by Buckethead, and then released again for free on May 31 with a soundtrack by James Paddock.In addition to WAD files, Doom includes a feature that allowed players to record and play back gameplay using files called demos, or game replays. Although the concept of speedrunning a video game existed before Doom, its release coincided with a wave of popularity for speedrunning, amplified by the online communities built on the nascent Internet.  Demos were lightweight files that could be shared more easily than video files on internet bulletin board systems at the time. As a result, Doom is credited with creating the video game speedrunning community. The speedrunning community for Doom has continued for decades. As recently as 2019, community members have broken records originally set in 1998. It has been termed "one of the longest-running speedrunning communities" as well as "the quintessential speedrunning game".

Notes
References
Sources
External links

Doom at MobyGames
The "Official" Doom FAQ