Born in Colorado, John Romero began programming at age 11 in the student-run computer labs of Sierra College in California. While still a teenager, he published Apple II games in hobbyist magazines such as Nibble. He briefly attended Sierra College before dropping out to work at Origin Systems, then Softdisk.
After repeated conflicts with management over the direction of game development, several Softdisk employees departed to form id Software in 1991. Romero became a key figure in the creation of several seminal games including Commander Keen, Wolfenstein 3D, Doom, and Quake, as well as serving as an executive producer on Raven Software's Heretic and Hexen.
In 1996 Romero was forced to resign from id Software for "not working hard enough". Romero then co-founded Ion Storm in Dallas, Texas with id co-worker Tom Hall, where he designed and produced Daikatana. That game's critical and commercial failure damaged Romero's reputation, earning him popular blame for questionable development decisions worsened by his name being hyped in the game's early marketing. In particular, an infamous 1997 ad (by Ion's then-CEO Mike Wilson) with the slogan "John Romero's about to make you his bitch" upset many people. Romero left with Tom Hall immediately after the release of Hall's Anachronox game and the subsequent closing of the Dallas Ion Storm office. The two then co-founded Monkeystone Games in July 2001.
Between 1999 and 2003, Romero was romantically involved with Stevie Case, a prominent female gaming industry figure who beat him in a Quake deathmatch. Until their breakup, Case was the chief operating officer of Monkeystone.
In October 2003, he joined Midway Games as Project Lead on Gauntlet: Seven Sorrows. While he continued to maintain his working relationship with Monkeystone, Lucas Davis took over running the office. The Monkeystone team moved to Austin, Texas to work on Midway's Area 51 until its release. Monkeystone Games closed in January 2005. John moved from Project Lead to Creative Director of Internal Studio during this time, but then left Midway in June 2005, only months before the completion of Gauntlet: Seven Sorrows.
On August 31, 2005 Romero confirmed that since leaving Midway he has been hard at work on an upcoming project at his newly opened development studio, preliminarily named Slipgate Ironworks. "For the record," Romero wrote, "I'm co-founder of a new game company in the Bay Area and am much better off in many ways than I was at Midway." A shroud of secrecy lies over the company and its projects.
Romero has been married three times, to Kelly Mitchell, Raluca Plesca, and Brenda Brathwaite, and has three children, Michael, Steven, and Lillia.
Levels by Romero
- E1M1: Hangar
- E1M2: Nuclear Plant
- E1M3: Toxin Refinery
- E1M4: Command Control (with Tom Hall)
- E1M5: Phobos Lab
- E1M6: Central Processing
- E1M7: Computer Station
- E1M9: Military Base
- E4M2: Perfect Hatred
- E4M6: Against Thee Wickedly
- MAP11: Circle of Death
- MAP15: Industrial Zone
- MAP17: Tenements
- MAP20: Gotcha!
- MAP26: The Abandoned Mines
- MAP29: The Living End
- Tech Gone Bad (2016)
Romero's head can be found within the final boss of Doom II (see MAP30: Icon of Sin). As the monster awakens, it makes an incomprehensible and evil-sounding noise, which is actually Romero's voice saying "To win the game you must kill me, John Romero" played backwards.
While designing levels for Doom, Romero documented several rules, among them:
- always changing floor height when I wanted to change floor textures
- using special border textures between different wall segments and doorways
- being strict about texture alignment
- conscious use of contrast everywhere in a level between light and dark areas, cramped and open areas
- making sure that if a player could see outside that they should be able to somehow get there
- being strict about designing several secret areas on every level
- making my levels flow so the player will revisit areas several times so they will better understand the 3D space of the level
- creating easily recognizable landmarks in several places for easier navigation 
- John likes listening to heavy metal music. He supplied Bobby Prince a large number of heavy metal records, which was the inspiration for the MIDI rock music used in Doom and Doom II.
- John Romero is a character in Mike "Cyb" Watson's modification MassMouth 2. In addition, Daikatana is given as a prize for saving Worm and killing Romero.
- In Action Doom, the first level contains an ad "Scuba Steve is a whiny little bitch", a reference to the Daikatana ad. A Daikatana box also sits on the table in the player's room on the final level.
- Masters of Doom
- This article incorporates text from the open-content Wikipedia online encyclopedia article John Romero.
- This article incorporates text from the open-content Wikipedia online encyclopedia article Ion Storm.
- Doom level design credits (archived)
- John Carmack Interviews, http://www.scribd.com/doc/479479/John-Carmack-Archive-Interviews