In computer software and media, an Easter egg is an intentional inside joke, hidden message or image, or secret feature of a work. It is usually found in a computer program, video game, or DVD/Blu-ray Disc menu screen. The name is used to evoke the idea of a traditional Easter egg hunt. The term was coined to describe a hidden message in the Atari video game Adventure that encouraged the player to find further hidden messages in later games, leading them on a 'hunt'.
The use of the term "Easter egg" to describe secret features originates from the 1979 video game Adventure for the Atari 2600 game console, programmed by employee Warren Robinett. At the time, Atari did not include programmers' names in the game credits, fearing that competitors would attempt to steal their employees. Robinett, who disagreed with his supervisor over this lack of acknowledgment, secretly inserted the message "Created by Warren Robinett". This message would only appear if a player moved his/her avatar over a specific pixel (the "Gray Dot") during a certain part of the game. When Robinett left Atari, he did not inform the company of the acknowledgment that he included in the game. Shortly after his departure, the Gray Dot and his message were exposed by a player who told Atari about his discovery. Atari's management initially wanted to remove the message and release the game again, but this was deemed too costly an effort. Instead, Steve Wright, the Director of Software Development in the Atari Consumer Division, suggested that they keep the message and, in fact, encourage the inclusion of such messages in future games, describing them as Easter eggs for consumers to find.
In addition to Robinett's name appearing in Adventure (1979), there are many other instances where the Easter egg idea has been implemented. The first text adventure game, Colossal Cave Adventure (1976), from which Adventure was fashioned, included several secret words. One of these was "xyzzy", a command which enabled the player to move between two points in the game world. In 2004, an Easter egg displaying programmer Bradley Reid-Selth's surname was found in Video Whizball (1978), a game for the Fairchild Channel F system. According to research by Ed Fries, the first known Easter egg in an arcade game was in Starship 1 (1977), programmed by Ron Milner. By triggering the cabinet's controls in the right order, the player could get the message "Hi Ron!" to appear on the screen. Fries described it as "the earliest arcade game yet known that clearly meets the definition of an Easter egg". The existence of this Easter egg wasn't published until 2017, leading Fries to suggest that, as more than one hundred arcade games predate Starship 1, earlier Easter eggs may still be undiscovered. Fries noted that some Atari arcade cabinets were resold under the Kee Games label and included changes to the hardware that would make the game appear different from the Atari version. Anti-Aircraft II (1975) included a means to modify the circuit board to make the airplanes in the game appear as alien UFOs. Fries surmised that this feature may have been intended for a Kee Games release. For this reason, and because it required a hardware modification, Fries questioned whether it met the definition of an Easter egg.
Since Adventure, there has been a long history of video game developers placing Easter eggs in their games.:19 Most Easter eggs are intentional - an attempt to communicate with the player or a way of getting even with management for a slight. Easter eggs in video games have taken a variety of forms, from purely ornamental screens to aesthetic enhancements that change some element of the game during play. The Easter egg included in the original Age of Empires (1997) is an example of the latter; catapult projectiles are changed from stones to cows.:19
More elaborate Easter eggs include secret levels and developers' rooms - fully functional, hidden areas of the game. Developers' rooms often include inside jokes from the fandom or development team and differ from a debug room in that they are specifically intended for the player to find. Some games even include hidden minigames as Easter eggs. In the LucasArts game Day of the Tentacle (1993), the original Maniac Mansion (1987) game can be played in its full version by using a home computer in a character's room.
Other Easter eggs originated unintentionally. The Konami Code, a type of cheat code, became an intentional Easter egg in most games, but originated from Konami's Gradius (1985) for the Nintendo Entertainment System. The programmer, Kazuhisa Hashimoto, created the code as a means to rapidly debug the game by giving the player's avatar additional health and powers to easily traverse the game. These types of codes are normally removed from the game before it is shipped but, in the case of Gradius, Hashimoto forgot to remove it and the code was soon discovered by players. Its popularity inspired Konami to reuse the code and purposely retain it for many of its future games as an Easter egg.
Technical issues may also create unintentional Easter eggs. Jon Burton, founder of Traveller's Tales, announced that many seemingly apparent Easter eggs in their Sega Genesis games came about as a result of introducing programming tricks to get around some of the difficulty they had in getting Sega's strict certification for their games, catching any exceptions during execution to bring the game back to a usable state as to pass certification. For example, hitting the side of the Sonic 3D Blast (1996) cartridge while it was slotted in the console would bring the game back to the Level Select screen, which Burton explained was the default exception handling for any unidentified processor error, such as when connectivity between the cartridge and the console's microprocessor was temporarily lost.
In computer software, Easter eggs are secret responses that occur as a result of an undocumented set of commands. The results can vary from a simple printed message or image to a page of programmer credits or a small video game hidden inside an otherwise serious piece of software.
In the TOPS-10 operating system (for the DEC PDP-10 computer), the
make command is used to invoke the TECO editor to create a file. If given the file name argument
love, so that the command reads
make love, it will pause and respond
not war? before creating the file. This same behavior occurred on the RSTS/E operating system, where TECO will provide this response. Other Unix operating systems respond to "
why" with "
why not" (a reference to The Prisoner in Berkeley Unix, 1977).
Some versions of the DEC OpenVMS operating system have concealed exit status codes, including a reference to the Monty Python Dirty Hungarian Phrasebook skit; "
exit %xb70" returns the message "%SYSTEM-W-FISH, my hovercraft is full of eels" while "
exit %x34b4" returns a reference to an early Internet meme: "%SYSTEM-F-GAMEOVER, All your base are belong to us".
Many personal computers have much more elaborate eggs hidden in ROM, including lists of the developers' names, political exhortations, snatches of music, or images of the entire development team. Easter eggs in the 1997 version of Microsoft Office include a hidden flight simulator in Microsoft Excel and a pinball game in Microsoft Word. Since 2002, Microsoft does not allow any hidden or undocumented code as part of its trustworthy computing initiative.
An Easter egg is found on all Microsoft Windows operating systems before XP. In the 3D Text screen saver, entering the text "volcano" would display the names of all the volcanoes in the United States. Microsoft removed this Easter egg in XP but added others. Microsoft Excel 95 contained a hidden action game similar to Doom (1993) called The Hall of Tortured Souls.
The Google search engine famously contains many Easter eggs, given to the user in response to certain search queries. For example, Google Maps once responded to a request for directions from New York City to Tokyo by telling the user to kayak across the Pacific Ocean.
The first Easter egg to appear after his death was in a 2012 update to the Mac App Store for OS X Mountain Lion, in which downloaded apps were temporarily timestamped as "January 24, 1984", the date of the sales launch of the original Macintosh.
While computer-related Easter eggs are often found in software, occasionally they exist in hardware or firmware of certain devices. On some home computers the BIOS ROM contains Easter eggs. Notable examples include some errant 1993 AMI BIOS that on November 13, 1993, proceeded to play "Happy Birthday" via the PC speaker repeatedly instead of booting, as well as several early Apple Macintosh models that had pictures of the development team in the ROM. These Mac Easter eggs were well-publicized in the Macintosh press at the time along with the means to access them, and were later recovered by an NYC Resistor team, a hacker collective, through elaborate reverse engineering. Similarly, the Radio Shack Color Computer 3's ROM contains code which displays what looks like three Microware developers on a Ctrl+Alt+Reset keypress sequence—a hard reset which discards any information currently in RAM.
Several oscilloscopes contain Easter eggs. One example is the HP 54600B, known to have a Tetris (1984) clone, and the HP 54622D contains an imitation of the Asteroids (1979) game named Rocks. Another is the Tektronix 1755A Vector and Waveform Monitor which displays swimming fish when Remote>Software version is selected on the CONFIG menu.
In the second and third hardware revision of the Minolta Dynax/Maxxum/Alpha 9 SLR camera, including all SSM/ADI upgraded cameras, an undocumented button sequence can be utilized to reconfigure the camera to behave like the Dynax/Maxxum/Alpha 9Ti and subsequently invoke support for the limited model's extra functions also in the black model.
The Commodore Amiga 1000 computer includes the signatures of the design and development team embossed on the inside of the case, including Jay Miner and the paw print of his dog, Mitchy. The Commodore Amiga models 500, 600, and 1200 each feature Easter eggs in the form of song titles by The B-52's as white printing on the motherboards. The 500 says "B52/Rock Lobster", the 600 says "June Bug", and the 1200 says "Channel Z". The Amiga OS software contains hidden messages.
Many integrated circuit (chip) designers have included hidden graphics elements termed chip art, including images, phrases, developer initials, logos, and more. This artwork, like the rest of the chip, is reproduced in each copy by lithography and etching. These are visible only when the chip package is opened and examined under magnification. The 1984 CVAX microchip implementation of the MicroVAX CPU contained in its etchings the Russian phrase in the Cyrillic alphabet "VAX: When you care enough to steal the very best", placed there because, "knowing that some CVAXs would end up in the USSR, the team wanted the Russians to know that we were thinking of them".
Easter eggs are found on films, DVDs, and Blu-ray Discs, often as deleted scenes or bonus features. Klinger states that their presence is "another signifier of artistry in the world of DVD supplements." According to Berardinelli and Ebert, most DVDs do not contain them and most examples are "inconsequential", but a very few, such as the one found on the Memento DVD release, are "worth the effort to seek out".
Unlike DVDs and computer games, broadcast radio and television programs contain no executable code. Easter eggs may still appear in the content itself, such as a hidden Mickey in a Disney film or a real telephone number instead of a 555 fictitious telephone number. A 2014 Super Bowl advertisement was leaked online in which a lady gives a man a real telephone number, which the advertiser had hidden as a marketing ploy; the first caller to the number received a pair of tickets to the game. The 1980s animated series She-Ra: Princess of Power featured a character called Loo-Kee who typically appeared once per episode, hidden in a single screenshot. At the end of the episode, the screenshot would be shown again and Loo-Kee would challenge viewers to locate him before revealing his hiding place.
Security author Michel E. Kabay discussed security concerns of Easter eggs in 2000, saying that, while software quality assurance requires that all code be tested, it is not known whether Easter eggs are. He said that, as they tend to be held as programming secrets from the rest of the product testing process, a "logic bomb" could also bypass testing. Kabay asserts that this undermined the Trusted Computing Base, a paradigm of trustworthy hardware and software in place since the 1980s, and is of concern wherever personal or confidential information is stored, as this may then be vulnerable to damage or manipulation. Microsoft created some of the largest and most elaborate Easter eggs, such as those in Microsoft Office. In 2005, Larry Osterman of Microsoft acknowledged Microsoft Easter eggs, and his involvement in development of one, but described them as "irresponsible", and wrote that the company's Operating System division "has a 'no Easter Eggs' policy" as part of its Trustworthy Computing initiative.
In 2006, Douglas W. Jones said, "some Easter eggs may be intentional tools used to detect illegal copying, others are clearly examples of unauthorized functionality that has slipped through the quality-control tests at the vendor". While hidden Easter eggs themselves are harmless, it may be possible for malware to be hidden in similar ways in voting machines or other computers.
Netscape Navigator contributor Jamie Zawinski stated in an interview in 1998 that harmless Easter eggs impose a negligible burden on shipped software, and serve the important purpose of helping productivity by keeping programmers happy.
Easter eggs have become more widely known to the general public and are referenced in contemporary artworks. They feature as key plot devices in:
The best Easter egg of all is the entire Maniac Mansion game, which appears on a computer in Doctor Fred's mansion. Users can play the original game in its entirety.
Microsoft’s developers hid multiple Easter Eggs in Word 95/97/2000.