Doom (series)/Trivia

General
""I have no problems with the demons in the game. They're just cartoons. And, anyway, they're the bad guys.""
 * One of the designers for the original Doom games, Sandy Petersen, was the original designer of the Call of Cthulhu tabletop game.
 * Sandy, by the way, is a Mormon. Which didn't stop him from helping to develop a game crammed with Satanic elements. Quoth the man himself to John Romero:


 * One of the secret levels in the Play Station port of the original games is a nightclub, complete with rave music.
 * The shotgun weapon sprites from the classic games are scanned images of a Tootsie Toy cap gun.
 * Doom 64 is a black sheep in the game for a good number of reasons; many of the monsters look different from the original games (most notably the Pain Elementals and Cacodemons seem to have swapped each other's bodies), the Barons of Hell and Hell Knights can hurt each other, now (normally, they're hardcoded against that), many of the weapons work differently (like a double-bladed chainsaw), and most importantly, you go back to hell despite destroying it at the end of Doom 2.
 * It also introduces the Nightmare Imps, an obvious shout-out to the Nightmare Spectres introduced in the Playstation version of the original Doom.
 * Doom 64 may be a sequel to the Play Station port of Doom, rather than the PC version. It uses the same sound effects and similar ambient music that PS 1 Doom used and was developed by Midway.
 * One step backwards from the engine used in Wolfenstein 3D is that sectors could not move horizontally. A result of this is that Doom doors, at least in stock maps, always open upwards, compared to the sideways-opening doors and pushwalls to secret areas in Wolf3D - it was not possible to replicate that sort of behavior on the Doom engine until the version that Hexen was built on.

Doom

 * Of the textures created from scanned pictures, one was based on one artist's snakeskin boots, while another was based on a photograph of another artist's wounded knee.
 * Port Overdosed: There has scarcely been a platform since Doom's release that has not received a version. The game is famous for its utter ubiquity.
 * Urban Legend of Zelda: Shortly after the Columbine school shooting, it was discovered that both boys were fans of Doom, which lead to claims that Dylan Klebold made custom WADs based off of the school for "training". While Klebold did make levels (and apparently, a mod that makes the game Bloodier and Gorier), none of them are modeled off of Columbine High, and when taken on their own reviewers have called the "Klebold Levels" average-to-sub par.
 * What Could Have Been: Tom Hall, one of the lead developers, had plans to wove in a more detailed story for the game and introduce several fleshed-out characters. John Carmack was heavily against this idea, claiming that doing so would overcomplicate the game, believing that the concept of "Shooting demons on Mars" would be enough to keep the players invested.

Doom II: Hell on Earth

 * The music for the ninth level, "The Pit," originally featured a piano as the main instrument. It was rejected because the rest of the development team wasn't keen on having piano music in Doom. Following this, the composer changed the piano to a harpsichord as a joke. The staff didn't notice it was a joke and accepted it.
 * John Romero's famous head on a stick was a joke on Romero by the artists, as the graphic used for the final boss's weak point was originally nothing out of the ordinary. His response was to record the equally famous backwards message that's heard when you face the final boss. Which, of course, is why it says, "To win the game, you must kill me, John Romero!"
 * One of the rock textures is actually from Wolfenstein 3D.

Final Doom

 * The TNT in TNT: Evilution actually stands for "The New Technology."
 * TNT also derives from the creators, Team TNT, who were a modding group for Doom; the commercial addition of Evilution to Final Doom was rather detested by the Doom community at the time, as TNT: Evilution was assumed to be another free megawad. This is an early example of a third-party mod being adopted by the original creators.
 * Dario and Milo Casali, the creators of The Plutonia Experiment, contributed four levels each to TNT: Evilution when it was a freeware Game Mod, only to have most of them rejected by id Software during its commercialization for being too resource-demanding for most contemporary computers. At least a few of them were reused in Plutonia.

Doom 3

 * Theresa Chasar, the female UAC scientist, was named after the sister of Tim Willits, the lead designer.
 * Think the Soul Cube/Artifact were unique weapons to Doom 3? Think again; Doom 64 had them first, in the form of the Unmaker and the Dark Claw, two unfortunately Dummied Out weapons that were originally supposed to work similarly to the Soul Cube/Artifact; the Unmaker even has "upgrades" to it, in the same manner the Artifact gains its powers.
 * Hey, It's That Voice!: In Resurrection of Evil one of the audio logs is spoke by Scott Menville, who did the voice of Robin in the Teen Titans cartoon. Hearing the voice of Robin speaking in utter terror about demons is pretty funny.
 * Sgt. Kelly is Lt. Kellaway from The Mask (animated version)
 * Knights of the Old Republic veterans may recognize Councilor Elliot Swann (played by Charles Dennis) as Davik Kang (the first game) or Lt. Dol Grenn (the second one). He also voiced Zherron in the latter game, but he's more difficult to recognize in that role.