The Columbine High School massacre occurred on April 20, 1999 at Columbine High School in Jefferson County near Littleton, Colorado, United States. Two students, Eric David Harris, age 18, and Dylan Bennet Klebold, age 17, executed a planned shooting rampage killing 12 other students and a teacher before committing suicide. It is considered to be the third worst school shooting in U.S. history, the worst being the 2007 Virginia Tech shooting and the second worst being the 2012 Sandy Hook Elementary School shooting.
Doomworld posted an editorial defending Doom and the staffers of the time participated in a variety of press interviews. Andrew "Linguica" Stine and Matthew "Mattrim" Dixon were interviewed by SFGate.com. Javier "Dukrous" Heredia defended Doom as part of an interview by CNN.
Doom connection and the Harris levels
Eric Harris was an enthusiast of the Doom series, owning some of the Doom novels and having designed Doom levels under the nicknames "REB", "Rebldomakr", and "RebDoomer". In a videotape recorded before the massacre, Harris expressed enthusiasm for the planned shooting, saying it would be like Doom. He also pointed out that the shotgun was "Straight out of Doom".
According to a statement made to government "investigators" of the Columbine massacre by then-CHS student David Proctor, who occasionally played Doom with Harris and Klebold via modem, Harris told him in 1999 that he'd created a level in Doom that was Columbine High School. Proctor added that another classmate had told him he'd heard the same. Though Harris did release several WADs, the alleged CHS level is not known to be on the Internet. After the massacre, many websites refused to provide downloads to any of the levels created by Harris, seeing the shooting as something from which the community should dissociate itself. While this position has largely dissipated, the maps are still rejected from inclusion on the idgames archive.
A PDF containing some of Harris' documents and personal writings  includes designs for some of his levels (page 112 onward). On page 272, Harris says "Doom is so burned into my head my thoughts usually have something to do with the game", while on page 321 he references the Doom novels. Harris also wrote about an idea for a seven level WAD known as Tier, though it is unknown if he actually went through with creating it. If he did finish making it, no copies of the WAD are known to be available to download.
Harris's UAC Labs WAD contains comments which appear somewhat disturbing in retrospect. For example, the description ends, "Good luck marine, and dont forget, KILL 'EM AAAAALLLL!!!!!", while the copyright section threatens, "You may NOT change a damn thing with this WAD, if you do, i will blow you up. And it will be cool". Two of Harris' WADs, Deathmatching in bricks! and Station, contain a new difficulty setting called "YA FREAKIN NUT!" as a replacement for the Nightmare! difficulty setting.
Copies of the following WAD files are known to exist:
- UAC Labs (uaclabs.wad)
- A two level single player WAD for Doom II: Hell on Earth. The most well-known of the Harris levels, it has an E1-style techbase theme. The WAD includes extra graphics that slightly increase the gore for the monster death animations and a modified ENDOOM screen containing the names of other WADs made by Harris. In the second level, the player is confronted with an enormous arena filled with Demons. New sound effects are used when monsters are gibbed, when monsters teleport in, when the Mancubus is attacked, and when the Cyberdemon sees the player; the music track "At Doom's Gate" is used in the first level, while the music track "Hiding The Secrets" is used in the second level. Both levels contain bugs that, when played with some source ports, prevent the player from achieving 100% completion in all three categories shown on the stats screen. The first level has a sector tagged as a secret that the player cannot access in any way (even with the no clip cheat activated), while the second level's item count is listed as having ten items that count toward the total item percentage, though the player can only get nine of them. UAC Labs was released on September 2, 1996.
- Deathmatching in bricks! (bricks.wad)
- A deathmatch level for Doom II: Hell on Earth, the name refers to the abundant use of brick textures. The level mainly consists of a number of high rise walkways which players must walk along. Dylan Klebold was credited for playtesting this level in the text file. It contains a new sky texture with a black background and white dots of varying sizes representing stars, as well as a new stats screen when the player beats the level showing a black background with red text displaying "PREPARE FOR YOUR NEXT FIGHT!!" and the text "BRICKS (KILL HIM!!)" as the map name on the stats screen. It contains new sound effects for the pistol, shotgun, chaingun, rocket launcher, and plasma gun. Deathmatching in bricks! was released on March 1, 1996 and took three days to create.
- Mortal Kombat Doom (fightme.wad)
- A deathmatch level for Doom II: Hell on Earth consisting of an arena containing four pillars on which the players start. Each player is given a berserk pack, the intention being that the players should fight each other using fists. It contains voice-overs from the Mortal Kombat games and a new music track. Mortal Kombat Doom was released on July 16, 1996 and took two hours to create.
- Hockey.wad (hockey.wad)
- A deathmatch level for Doom II: Hell on Earth consisting of an ice hockey rink and surrounding stadium. It contains new sound effects for the pistol, shotgun, chaingun, rocket launcher, and plasma gun. Hockey.wad was released on June 13, 1996 and took an hour and a half to create.
- KILLER (killer.wad)
- A deathmatch level for Doom II: Hell on Earth consisting of a large open grass arena containing several buildings with weapons. The respawn/teleport sound was changed to Duke Nukem saying the line, "You're pissing me off". The music used in this level is taken from the Zedek's Tomb level in Hexen: Beyond Heretic. KILLER was released on July 19, 1996 and took two hours to create.
- Station (station.wad)
- A techbase-themed deathmatch level for Doom II: Hell on Earth consisting of several rooms connected by a single corridor. This WAD was in the top 25 deathmatch WADs on AOL at one point according to the ENDOOM screen in uaclabs.wad. It contains a new sky texture and new sound effects for the pistol, chaingun, rocket launcher, plasma gun, and BFG 9000; the sound for the BFG 9000 was changed to Bruce Campbell saying the line, "Swallow this," from the Evil Dead 2 film. Additional credits for this WAD were given to the creator of a WAD called DeathWorld II: Fragland (made by Tom J. McClure on April 28, 1996, although his name is not mentioned and it is simply called "Fragland" in the text file for Station) for the pool idea and someone named Excaluber for additional ideas. Station was released on July 25, 1996 and took an hour and a half to create.
- Outdoors (outdoors.wad)
- A deathmatch level for Doom/The Ultimate Doom. Outdoors was released on July 17, 1995. It is in the Rebdoomer directory at acolumbinesite.com.
The ENDOOM screen for uaclabs.wad mentions the following WADs, although no copies of them are known to be publicly available to download:
- realdoom (a patch, most likely for his realdeth WAD, which was consistently mentioned in the text files for all of the Harris levels; Harris encouraged the reader to email him to ask about it)
- coolname.zip (in the Rebdoomer directory at acolumbinesite.com, though it is not mentioned on the ENDOOM screen in uaclabs.wad)
- Wikipedia article about the Columbine High School massacre
- "No easy explanation for Columbine killings" – CNN article referencing Doomworld (April 28, 1999)
- "Doom fans say blame for school killings is unjustified" - sfgate.com article interviewing Andrew Stine (April 22, 1999)
- Doomworld - The Top 10 Infamous WADs - UAC Labs can be downloaded here
- Columbine Attack Government Document Library - Links to most of the 30,000+ pages of public domain government documents related to the Columbine massacre
- Rebdoomer Archives - Various levels by Harris can be downloaded here