Chapter 1
1. I loved the arcade: Marty Stratton. Unless noted otherwise, all quotes from Marty Stratton come from interviews conducted between February and April 2017.

2. In 2008, following nearly two years: "Doom 4 Announced," IGN.com, http://www.ign.com/articles/2008/05/07/doom-4-announced.

3. Speaking to anonymous sources close to Doom 4: "Five Years And Nothing To Show: How Doom 4 Got Off Track," Kotaku.com, https://kotaku.com/five-years-and-nothing-to-show-how-doom-4-got-off-trac-468097062.

4. Leaked footage from an alpha prototype: "Trailer for cancelled DOOM 4 leaks," TechnoBuffalo.com, https://www.technobuffalo.com/2015/05/19/trailer-for-cancelled-doom-4-leaks/.

5. More details came to light when Noclip: O'Dwyer, Danny. “DOOM Resurrected [Part 1] - To Hell & Back (DOOM Documentary)”. YouTube video, 28:27. Posted December 2016. https://www.youtube.com/watch?v=PS6SBnccxMA.

6. Carmack cited ZeniMax's unwillingness: "id co-founder Carmack pushes reality with Oculus VR," USA Today, https://www.usatoday.com/story/tech/2014/02/03/john-carmack-on-oculus-rift/4938887/.

Chapter 2

1. I started out at Naughty Dog: Hugo Martin. Unless noted otherwise, all quotes from Hugo Martin come from interviews conducted between February and April 2017.

2. Martin, a film buff long before he broke into Hollywood: "Punch For Punchline: Watch How Jackie Chan’s Unique Brand of Action Comedy Hits Harder Than Others,'" https://www.moviemaker.com/archives/moviemaking/acting/jackie-chan-action-comedy-video/.

3. Martin loved the analogy: "Speaker Q&A: Kurt Loudy and Jake Campbell break down the combat philosophy of DOOM," GDConf.com, http://www.gdconf.com/news/speaker-qa-kurt-loudy-jake-campbell-break-combat-philosophy-doom/.

4. Thus the clash, explained by art director Shinichiro Hara: "How Doom’s Glory Kills Maintain Momentum," Rock Paper Shotgun, https://www.rockpapershotgun.com/2016/07/15/doom-glory-kills-mechanic/.

5. The team decided on 16 animations per enemy: Ibid.

6. I can't tell you how many articles were written: "The glorious gore of 'Doom' chainsaw kills," Engadget, https://www.engadget.com/2016/05/16/doom-chainsaw-kills-gallery/. (Author: Just as one example.)7. Just a few weeks beforehand: "How Doom reveals its secrets like a Frank Frazetta painting," VentureBeat.com, https://venturebeat.com/2016/07/02/how-doom-tells-players-part-of-the-story-and-leaves-them-guessing/.

Chapter 7

1. A first-person shooter designed to capitalize: "Prerelease:Doom (PC, 1993)," TCRF.net, https://tcrf.net/Prerelease:Doom_(PC,_1993)#Press_Release.

2. Ibid.

3. The engine for Doom was running even in January: John Romero. Unless noted otherwise, all quotes from John Romero come from interviews conducted between February and April 2017.

4. You should make your first level last: IGN. “We Play Doom With John Romero”. YouTube video, 1:30:32. Posted December 2013. https://www.youtube.com/watch?v=YUU7_BthBWM.

5. I made the room dark: ""Devs Play" S01E05 - Doom (Part 3 - Map 2 Nuclear Plant) 60fps [3/10]". YouTube video, 21:55. Posted January 2015. https://www.youtube.com/watch?v=yAoDeRXWXw4 (Author's note: Romero, interviewed by Double Fine developer JP LeBreton, offers a detailed walkthrough of the entire level. This video is worth watching for anyone interested in a blow-by-blow breakdown of how it came together.)

6. Twenty-two years later, feeling the urge: Romero, John. Twitter post. January 15, 2016. https://twitter.com/romero/status/688054778790834176. (Author's note: Romero uploaded a twist on E1M4 a few months later. You can find it here: https://twitter.com/romero/status/725032002244759552.)

7. John Carmack got in on the joke: "Final Boss," Doom Wiki, http://doom.wikia.com/wiki/Final_Boss.

Chapter 8

1. The developers at id had made a special point: "Prerelease:Doom (PC, 1993)," TCRF.net, https://tcrf.net/Prerelease:Doom_(PC,_1993)#Press_Release.

2. Both consume the same bullets: "Pistol," Doom Wiki, http://doom.wikia.com/wiki/Pistol.

3. and both guns inflict between five and 15 damage: "DOOM Weapon Damage Information," doom2.net, http://www.doom2.net/single/weaponfaq.html.

4. Pick up a Berserk Pack, however: Ibid.

5. The rocket launcher, a real-world weapon invented: "Dr. Robert H. Goddard, American Rocketry Pioneer," NASA.gov, https://www.nasa.gov/centers/goddard/about/history/dr_goddard.html.

6. Upon making contact with a monster or any surface: "Frequently Asked Questions About the BFG9000," gamers.org, http://www.gamers.org/docs/FAQ/bfgfaq/.

Chapter 9

1. Its feature set is so thorough: “We Play Doom With John Romero”. YouTube video, 1:30:32. Posted December 2013. https://www.youtube.com/watch?v=YUU7_BthBWM.

Chapter 10

1. Romero had co-authored DoomEd: "Why John Carmack Chose NeXT For Developing 'Doom' And Other Favorites," Forbes.com, https://www.forbes.com/sites/quora/2016/09/01/why-john-carmack-chose-next-for-developing-doom-and-other-favorites/#38c561fd14d1.

2. The news post he had found was an announcement: "The New Technology: Evilution (1995/10/27 Press Release)," Google Groups, https://groups.google.com/forum/#!msg/alt.games.doom/Fhfl5PHTbVk/0eSgX8fkDJcJ.

3. I was a huge Wolfenstein 3D fan: "viggles." Unless noted otherwise, all quotes from viggles come from interviews conducted between February and April 2017.

4. was too terrified to get past the first demons: "Scwiba." Unless noted otherwise, all quotes from Scwiba come from interviews conducted between February and April 2017.

5. There are new releases on a daily basis: "Skillsaw." Unless noted otherwise, all quotes from Skillsaw come from interviews conducted between February and April 2017.

6. Ancient Aliens and Absolutely Killed earned Cacowards: "The 13th Cacowards," Doom World, https://www.doomworld.com/23years/.

7. and Viggles published Brigandine: "Brigandine [RC2, updated 2017-05-13]," Doom World, https://www.doomworld.com/forum/topic/92776-brigandine-rc2-updated-2017-05-13/.

Icon of Sin: Chapter 1

raked in over $100,000 a day for id: "'Doom' Turns 20: We Take A Look At The Game's History," International Business Times, https://www.ibtimes.com/doom-turns-20-we-take-look-games-history-1505336.

only accounted for $9 shareware purchases: Ibid.

return to fast, violent and masterful play: "BLACKROOM: A New FPS from Romero & Carmack," Kickstarter, https://www.kickstarter.com/projects/nightworkgames/blackroom-a-new-fps-from-romero-and-carmack/description.

the kind of gameplay, look and innovative: Ibid.

Icon of Sin: Chapter 3

Mockingbird Software beat Romero to the punch: "REKKR: Doom mod," ModDB.com, https://www.moddb.com/mods/rekkr.

An overview of REKKR posted on: "REKKR V1.16," Doom World, https://www.doomworld.com/forum/topic/90862-rekkr-v115/.

originally a mold of William Shatner’s Captain Kirk: "Was Michael Myers' Halloween Mask William Shatner's Face?", StarTrek.com, http://www.startrek.com/article/was-michael-myers-halloween-mask-william-shatners-face.