An Easter egg is a message, image, or feature hidden in software, a video game, a film, or another—usually electronic—medium. The term used in this manner was coined around 1980 by Steve Wright, the then-Director of Software Development in the Atari Consumer Division, to describe a hidden message in the Atari video game Adventure, in reference to an Easter egg hunt.
The earliest known video game Easter egg is in the 1973 video game Moonlander, in which the player tries to land a lunar module on the Moon; if the player opts to fly the module horizontally through several of the game's screens, they encounter a McDonald's restaurant, and if they land next to it, the astronaut will visit it instead of standing next to the ship. The earliest known Easter egg in software in general is one placed in the "make" command for PDP-6/PDP-10 computers sometime in October 1967–October 1968, where if the user attempts to create a file named "love" by typing "make love", the program responds "not war?" before proceeding.
Origin
The use of the term "Easter egg" to describe secret features in video games originates from the 1980 video game Adventure for the Atari 2600 game console, programmed by the employee Warren Robinett. At the time, Atari did not include programmers' names in the game credits, both to prevent competitors from poaching its developers as well as to deny developers a means to bargain with the management of the new owners, Warner Communications. Robinett, who disagreed with his supervisor over this lack of acknowledgment, secretly programmed the message "Created by Warren Robinett" to appear only if a player moves their avatar over a specific pixel (dubbed the "Gray Dot") during a certain part of the game and enters a previously "forbidden" part of the map where the message can be found. 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 discovered by a player. Atari's management initially wanted to remove the message and release the game again, until this was deemed too costly. 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 video games While Robinett's message in Adventure led to the first use of the phrase "Easter egg", Easter eggs were included in previous video games. The earliest known video game Easter egg is in Moonlander (1973), in which the player tries to land a spaceship on the Moon. If the player flies far enough horizontally, they encounter a McDonald's restaurant, and if they land next to it, an astronaut will visit it instead of standing next to the ship. Other early known Easter eggs include one in the first text adventure game, Colossal Cave Adventure (1976), from which Adventure was fashioned, which includes several secret words. One of these is "xyzzy", a command which enables the player to move between two points in the game world. According to research by Ed Fries, one of the earliest Easter eggs in a graphical video games could be found in Starship 1 (1977), programmed by Ron Milner. By triggering the cabinet's controls in the right order, the player can have the message "Hi Ron!" appear on the screen. Fries describes it as "the earliest arcade game yet known that clearly meets the definition of an Easter egg". The existence of this Easter egg was not 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 says that some Atari arcade cabinets were resold under the Kee Games label and include changes to the hardware that make the game appear different from the Atari version. Anti-Aircraft II (1975) includes a means to modify the circuit board to make the airplanes in the game appear as alien UFOs. Fries surmises that this feature may have been intended for a Kee Games release. For this reason, and because it requires a hardware modification, Fries questions whether it meets the definition of an Easter egg. Multiple games released for the Fairchild Channel F, including Video Whizball (1978), were also have found to have easter eggs put in place by programmers Bradley Reid-Selth and Micheal K. Glass.
Since Adventure, there has been a long history of video game developers placing Easter eggs in their games. Most Easter eggs are intentional—an attempt to communicate with the player or a way of getting even with management for a perceived slight. Easter eggs in video games take 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.
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. Similarly, a programmer included the whole of TimeSplitters 2 (2002) within Homefront: The Revolution (2016), accessed by using a special code at an in-game arcade cabinet.
Other Easter eggs originated unintentionally. The Konami Code, a type of cheat code, became an intentional Easter egg in most games, but it 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, said 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 is slotted in the console will bring the game back to the Level Select screen, which Burton explains is the default exception handling for any unidentified processor error, such as when connectivity between the cartridge and the console's microprocessor is temporarily lost.
In computing Software
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 mainframe computer), the command is used to invoke the TECO editor to create a file. If given the file name argument , so that the command reads , it will pause and respond before creating the file. The Easter egg was added sometime between October 1967 and October 1968 by William F. Weiher at the Stanford AI Lab to the COMPIL program for the PDP-6, which was then used in the TOPS-10 operating system, making it the first Easter egg in a software program. This same behavior occurs on the RSTS/E operating system, where TECO will provide this response. Other Unix operating systems respond to "" with "" (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; "" returns the message "%SYSTEM-W-FISH, my hovercraft is full of eels" while "" returns a reference to an early Internet meme: "%SYSTEM-F-GAMEOVER, All your base are belong to us".
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.
The Debian operating system's package tool apt-get has an Easter egg involving an ASCII cow when variants on are typed into the shell.
An Easter egg is found on all Microsoft Windows operating systems before XP. In the 3D Text screen saver, entering the text "volcano" will display the names of all the volcanoes in the United States. Microsoft removed this Easter egg in XP but added others. In Windows Vista and later, by launching a screensaver executable (introduced with Windows Vista) on the command line with the /p65552 flag, for example launching the "bubbles" screen saver with bubbles.scr /p65552 command-line parameter, it runs as desktop wallpaper. Microsoft Excel 95 contains a hidden minigame called The Hall of Tortured Souls, which consists of a small explorable 3D room in a visual style similar to Doom (1993). The names of the Excel's programmers are written on the room's walls.
The Google search engine famously contains many Easter eggs, given to the user in response to certain search queries.
Steve Jobs banned Easter eggs from Apple products upon his return to the company. The first Easter egg to appear after his death is in a 2012 update to the Mac App Store for OS X Mountain Lion, in which downloaded apps are temporarily timestamped as "24 January 1984", the date of the sales launch of the original Macintosh.
The Python programming language and its ecosystem of libraries include various Easter eggs.
Firmware While computer-related Easter eggs are often found in installed software, occasionally they exist in the firmware of certain devices. On some home and early personal computers the ROM contains Easter eggs, including lists of the developers' names, political exhortations, snatches of music, or images of the entire development team.
The palmtop PC HP 200LX (1994) includes an undocumented hex calculator HEXCALC.EXM. The built-in maze game "Lair of Squid" incorporates a hidden gallery of the software developers. In test mode it displays several poems.
Other notable examples include some versions of the AMI BIOS that on 13 November 1993, proceeded to play "Happy Birthday" via the PC speaker repeatedly instead of booting, as well as several early Apple Macintosh models that have photos 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 ++ 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 (1985) 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.