An easter egg is a message that is hidden or otherwise not immediately evident and is meant to amuse players and often used by the designers to refer to influences, development jokes, pet characters, previous works, or preferences.
Attempting to leave the game will give you a random message to go with "Press Y to Quit to dos" (Ex. Just leave. When you come back, I'll be waiting with a bat.- Don't leave yet - there's more Demons to toast!- You're trying to say you like DOS better than me, right?)
In released versions of Doom prior to V1.4, E1M4: Command Control contained a swastika design on the floor of one room. According to John Romero, it was placed there as a homage to Wolfenstein 3D. Alpha versions of this level, dated April 2 and May 22, 1993, included the same room, but did not have the swastika design. [1] The swastika was removed in V1.4 of Doom. The presence of a swastika would have caused Doom to be banned in Germany, and not just restricted to adults due to the game's graphic violence. Romero has also given a few different explanations as well... From censoring it from complaints from parents, and also that a veteran asked him to remove it.[1]
"Yes, [in Commander Keen 5] there is a swastika in one of the levels, one of my levels to be exact, but I removed it shortly after the game was released because people were upset that an evil symbol was in a cute kid's game (the changed version is in the screenshot). It was a premonition of things to come, namely, Wolfenstein 3D. I also put a swastika in Doom's E1M4 as a Wolf3D reference, but I changed it later for the exact same reason." – John Romero [1][2]
E4M1: Hell Beneath includes the letters "NIИ" in a part of the level, a reference to Nine Inch Nails, the American industrial rock band.[3] Also, id software's next game, Quake, would feature sound and music by the band's frontman, Trent Reznor. Additionally, ammunition for the nail-gun and super nail-gun –a crate of nails– would be inscribed with "NIИ" on each of its faces.
Doom II
John Romero's head on a stick
Romero's head
In MAP30: Icon of Sin, after the player teleports into the huge room with the head of the final boss, a strange, unintelligible noise is played, presumably saying: "I will lie in bricks at the end of the ambush". This is stored in the Doom2 wad file as DSBOSSIT, and if reversed it becomes a voice saying "To win the game, you must kill me, John Romero". The voice is shifted down in pitch and is that of John Romero himself.
In the same level, John Romero's severed head on a stick features as the main boss creature, although the head is hidden behind the face of the final boss, and can only be approached with the noclip cheat. The player must indeed kill it in order to win the game.
Both levels include Wolfenstein textures and SS Nazis that attack the player.
In MAP31, SS Nazis take the place of soldiers and Demons are found in place of the dogs.
A Cyberdemon is in the place of Hans Grosse in MAP32; the name of this map also comes from Hans Grosse's name.
In the last room in MAP32 there are four Commander Keens hanging on ropes. They must be killed in order to exit the level.
At the beginning of MAP32, the message "You'd better blaze through this one!" is displayed; Billy Blaze is Commander Keen's real name.
if you clear a map in over 1 hour on the clear screen a text will appear over the timer that says "sucks" when the time reaches 1 hour
No Rest for the Living
In the first level of the Doom II expansion: No Rest for the Living may be found a hidden message is written on the walls and ceiling of a room, which must be reached before they meet the 30 seconds after starting the game and push a switch.
The message reads "The castle was here", the word castle being a direct allusion to Russell "The Castle" Meakim, one of the game designers, employed by Nerve Software.
Final Doom
Two of the wall textures in Team TNT's TNT: Evilution, CR64HBRM and METAL-RM, have large blood stains which spell the name "Romero", a reference to John Romero.
There is a hidden room in MAP17: Processing Area next to the room containing the blue key that can only be accessed by using the noclip cheat. Several Demons are inside and will teleport out once the key is collected. In this room the player can see "Tom" and "NIИ" in large, glowing blue letters on the north and south walls respectively.
Doom 64
In Doom 64, if a player dies and waits several seconds, messages will start to appear at the top of the screen every once in a while, usually taunting the player (e.g. "HAHAHAHAHAHAH!!!!", "LOOK AT THOSE DEMON FEET!", etc.).
In level MAP03: Main Engineering is a time when, on entering the second room, generating a huge pedestal where the blue key is triggered. However, if the player jumps inside the circle where it will create the pedestal after the key appears, you will be trapped in the machine unable to leave but you won't die. The legend appears on the sides of the pedestal base "I suck at making maps" repeated on all four sides.
Doom 3
At the start of the game, the player can access a communal area where an arcade machine is placed named Super Turbo Turkey Puncher 3. The game is formed mostly from Doom 1 graphics, and features the fist, status bar face, gibs and a background which is clearly a screenshot from E4M9 of Ultimate Doom. The game logo alludes to Street Fighter Alpha 3 and the fictional developer Nabcon to Capcom.
If the player earns a score of 25,000 on Super Turbo Turkey Puncher 3, an e-mail from Marine HQ will be sent to your PDA first congratulating you for setting a new high score and being a shining example of humanity by punching defenseless turkeys and then notifying you that you been deducted two days of paid leave.
In the Primary Excavation: Artifact Dig level, one of the tablets bears the original Doom cover but with fewer demons and the Doomguy holding the soul cube in his hands. His head is cutt off from the tablet.
After returning to Mars from Hell, a terminal in the CPU Transfer Bay Entrance displays a red screen. An email can be downloaded from this terminal, containing a rather tongue-in-cheek message written by the demons on proper human sacrifice techniques.
In the final room before the Cyberdemon encounter, a small id Software logo can be found on one of the bricks in a corner. Approaching this turns the crosshair into a mouse arrow as would happen if the player approached a terminal. Clicking this opens a secret room which contains a PDA. Picking this PDA up downloads special "thank you" messages from the id Software staff.
Throughout the entire game there are 2 posters of the UAC being presented on several walls.
One of them ironically says "Bringing Mankind One Step Closer To Heaven".
The other one says "Changing The Face Of Mars" with a reimagined picture of the so called Face on Mars beneath it. This is a reference to the humanoid looking rock formation that was discovered by one of the orbiters sent to Mars back in 1976 by NASA.
Elizabeth McNeil's name derives from one of the programmer's at Nerve Software, Darin McNeil.
The terms Phobos and Erebus are throwback references to the original Doom game from 1993, with Phobos being one of the two moons of mars, and Erebus being one of the later hell levels, called Mount Erebus.
In Phobos Labs Sector 2, in the areas Research Sector A and Artifact Research, where Elizabeth McNeil has her office too, there are several offices whose doors bear the names of the developers at Nerve Software, similar to the cell block section in Delta Labs Sector 2a in the main game Doom 3, where only names of id Software members are presented. With that being the case, Darin McNeil's office is located right in front of Elizabeth's office.
There are three arcade cabinets scattered throughout the whole game, which are all in the same vein as Super Turbo Turkey Puncher 3.
The first one can be found in the office of Sergeant B. James in the Erebus Labs. The game is called "Sarge's Big Game Hunt" and resembles a classical Artillery Game such as Scorched Earth. The player must shoot at balloons that are holding up grizzly bears in the air.
The second one can be found in the kitchen area of Erebus Control and is called "Hellanoid". It is the very same principal as Arkanoid and unlike "Sarge's Big Game Hunt" seems to have a limited amount of levels.
RoE related page of martianbuddy.com
The third and last one can be found in the kitchen area of Phobos Labs Sector 2 and is called "Martian Buddy Blaster". With the original BFG asset from the very first doom game, the player needs to shoot astroids approaching him but has to save the also approaching Martian Buddies. If a certain score is reached the game will end and an e-mail is sent to the players PDA. It informs him that he is a "true hero" for saving all the Martian Buddies and that a special gift awaits him if he visits the web adress "martianbuddy.com/blaster.html". Back then, if the adress was typed into a real browser, it would show a page giving a hint to where the BFG in Phobos Labs Revisited was located and also reveal the code for an alleged martian buddy cabinet that was supposedly located somewhere in the game. However, there doesn't exist a single martian buddy cabinet throughout the whole expansion pack. The given code however, 634, is given to the player in-game regadless, through the PDA of Patrick Hook in the Delta Labs, but only for two regular cabinets.
In the Delta Labs section the last PDA of the game can be found. It belongs to a Patrick Hook, who was a designer at Nerve Software. He has a mail from a Delta Security Chief telling him the code for the cabinets in the nearby area. The name of that security chief is Sean Mitchell, who was a programmer at Nerve Software.
Chex Quest contains many levels leftover from the original 3-episode Doom albeit trimming to 5 levels.
The texture CEMPOIS has a blackboard and in the bottom right-hand corner of said board, is the equation: √2 = chuck. Charles Jacobi was the Art Director/Lead Artist for Chex Quest.
A secret room in E1M2 contains pictures of all the people that worked on Chex Quest.
In Pitfall: The Mayan Adventure, typing IDDQD or IDKFA shows a picture of the Pitfall staff.
Wrack
The loading screen for Wreck features protips, which provide useful tips on playing the game. Some of them have references to Doom.
"To win the game you must kill me, John Ro- Oh, nevermind." - This refers to the reversed Icon of Sin chant from Doom II.
"To kill enemies, shoot at them until they die." - Refers to the sarcastic Doom playing tip from a Gamepro magazine, "To kill the Cyberdemon, shoot at it until it dies!", which spawned the protip internet meme.
In addition to the protips, Wrack also features discouraging joke messages that show when the player tries to leave the game, much like those seen in Wolfenstein 3D, Doom, and Doom II.
