Did you know that Doom's intermission screen shows the Tower of Babel being built during the second episode?
Did you know that the level names in Thy Flesh Consumed, the final episode that was introduced in The Ultimate Doom, are all taken from passages in the King James Version of the Bible?
Did you know that the soul sphere was originally supposed to be an "extra life" powerup, before the concept of lives was dropped during development?
Did you know that the chainsaw and super shotgun weapons in the game were inspired by the Evil Dead series of movies?
Did you know that the super shotgun blast at close range will do about as much damage as the direct hit of a rocket from a rocket launcher or cyberdemon?
Did you know that the nearby presence of monsters is indicated to the player by a sound?
Did you know that Doom 3 contains numerous references to classic Doom?
Did you know that Doom contains a shocked status bar face expression which is rarely displayed due to a bug in the game?
Did you know that Doom's automap was originally intended to include a minigame as an easter egg?
Did you know that the Nightmare! skill level was added as a joke, in response to comments that the game was too easy?
Did you know that Doom Alpha version 0.5 had an old version of MAP10: Refueling Base from Doom II in it?
Did you know that the Doom II map Circle of Death takes its automap name from the "Hoe of Destruction" found in Ultima VII?
Did you know that the name "Doom" comes from a scene in the movie The Color of Money?
Did you know that vanilla Doom can be launched with skill level set to 0, which makes levels empty of all monsters, items, and decorations?
Did you know that many sound effects used in the original Doom games were acquired from Sound Ideas' General series sound effects library, which is why they can be heard in various movies and television shows?, and did you also know that tech-savvy hackers of IWADs can obtain those sounds for amateur moviemaking sound effects, though some fan websites for Doom also have those same sounds?
Did you know that pain elementals and arch-viles cannot normally be the primary target of another monster?
Did you know that the -turbo command line parameter was added to Doom by John Carmack as a prank to allow Shawn Green to beat John Romero in a deathmatch?
Did you know that in vanilla Doom it is possible to render an arch-vile attack harmless by saving and loading the game while the arch-vile is performing the offensive?
Did you know that a bug in the Doom engine allows certain mancubus shots to go through walls?
Did you know that John Romero built the level Perfect Hatred in six hours?
Did you know that that arch-vile can, eventually, kill themselves from the splash damage from their own attack?
Did you know that Spawning Vats was the first proper Doom level ever made?
Did you know that many of Doom II's resources not featured in the final release of the original 3 episodes were originally implemented in the beta versions, albeit with some alterations?
Did you know that megawad]s and total conversions are actually PWADs that come close to the file size of non-shareware/demo IWADs, though cult classic total conversions like Chex Quest were distributed as an IWAD.
Did you know that as the development of the game that would eventually become Doom started id Software briefly considered basing it on the movie Aliens?
Did you know that, in Doom versions up to 1.1, it was possible to run the game on three monitors at once, giving a 270-degree field of vision?
Did you know that the -avg command line parameter refers to Austin Virtual Gaming, a shop near the University of Texas set up in 1994 for pay-for-play Doom multiplayer?
Did you know that the abbreviation BFG stands for "Big Fucking Gun"?
Did you know that John Carmack went to juvenile detention for trying to steal an Apple II computer when he was a teen?
Did you know that Doom was released one day after a U.S. Senate hearing on violent video games?
Did you know that id Software did not release a shareware demo of Doom II?
Did you know that John Romero coined the term "deathmatch" while he and John Carmack were developing Doom's multiplayer mode?
Did you know that the Doom music was based on music by bands including Pantera, AC/DC, Metallica, Slayer and Alice in Chains?
Did you know that in Doom version 1.0 map E1M4: Command Control contained a swastika-shaped structure?
Did you know that Doom's protagonist, the marine, has made cameo appearances in Duke Nukem 3D and in the PC version of Tony Hawk's Pro Skater 3?
Did you know that id Software coined the initial concept of Quake before developing Doom?
Did you know that while many monsters of the same species will not normally fight each other they may do so if one causes a barrel explosion which hurts another?
Did you know that splash damage in the original Doom games is computed only from the horizontal distance between the explosion and the affected thing, which can be used to harm targets far above or below the blast?
Did you know that in the original Doom games the speed of projectiles does not take the vertical dimension into account? For example, this causes monsters' fireballs to travel extremely fast when fired from above or below.
Did you know that the Wolfenstein SS in the Doom II secret levels MAP31 and MAP32 have a blue uniform, even though actual SS Nazi soldiers had a black one?
Did you know that the graphic lumps for the episodes in Doom menu are still in DOOM2.WAD?
Did you know that the invulnerability powerup not affecting the sky, long thought to be a feature, is actually a bug?
Did you know that it is possible to run Chex Quest with Doom 1 graphics by using DOOM2.WAD as a PWAD? Though it can crash the game on some source ports.
Did you know that DOOM II was released before the original DOOM was released onto other computer platforms.