Easter egg (software)

An Easter egg is an intentional inside joke, a hidden message or image, or a secret feature of a work (often 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 led Atari to encourage further hidden messages in later games, treating them as Easter eggs for players to find.

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 would not include programmers' names in the game credits, fearing that competitors would attempt to steal away their employees. Robinett, who disagreed with his supervisor over the lack of acknowledgment as well as other issues, secretly inserted the message "Created by Warren Robinett" which would only appear if a player moved their avatar over a specific pixel (the "Gray Dot") during a certain part of the game. Robinett had not told anyone at Atari about this by the time he left the company. Shortly after his departure, the Gray Dot and his message were exposed by a player who told Atari about their discovery. Atari's management initially wanted to release the game again after removing the message, but it would have been a costly effort. Steve Wright, the Director of Software Development of the Atari Consumer Division, suggested that they keep the message and encourage future games to include such messages, describing them as Easter eggs for consumers to find.

In addition to Robinett's name in Adventure (1979), there are many other instances where this Easter egg idea has been implemented. The first text adventure game, Colossal Cave Adventure (1976), which Adventure was fashioned from, included a few secret words including "xyzzy" that enabled the player to move between two points in the game world quickly. In 2004, an Easter egg was found in Video Whizball (1978), a game for the Fairchild Channel F system, displaying programmer Bradley Reid-Selth's surname. According to research by Ed Fries, the first known Easter egg in an arcade game came from Starship 1 (1977), programmed by Ron Milner; although, its existence wasn't published until 2017. By triggering the cabinet's controls in the right order, the player could get the message "Hi Ron!" displayed to them on the screen. Fries described it as "the earliest arcade game yet known that clearly meets the definition of an Easter egg" but suggested 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 on the hardware that would make the game appear different from Atari. Anti-Aircraft II (1975) included a means to modify the circuit board to make the airplanes in the game appear as alien UFOs, which Fries surmised would have been for a Kee Games' release, but argued if this is a true Easter egg since it requires hardware modification.

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