Easter eggs are messages, videos, graphics, sound effects, or an unusual change in program behavior that sometimes occur in a software program in response to some undocumented set of commands, mouse clicks, keystrokes or other stimuli intended as a joke or to display program credits. An early use of the term Easter egg was to describe a message hidden in the object code of a program as a joke, intended to be found by persons disassembling or browsing the code.
Some Examples of Easter Eggs are:
SOFTWARE BASED
Many personal computers have elaborate eggs hidden in ROM, including lists of the developers’ names, political exhortations, snatches of music, and (in one case) 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 Word (see Easter eggs in Microsoft products).
The Palm operating system has elaborately hidden animations and other surprises. The Debian GNU/Linux package tool apt-get has an Easter egg involving an ASCII cow when variants on “apt-get moo” are typed into the shell.
Many new video games contain easter eggs, like Microsoft’s very popular Halo series.
An Easter Egg is found on all Microsoft Windows Operating Systems prior to XP. In the 3D Text screen saver, entering the text “volcano” will display the names of all the known volcanoes that exist in the world. Microsoft removed this Easter Egg in XP but added others.
One which continues till Windows XP is to simultaneously hold the Alt, shift, and the number 2 keys in the Solitaire game to produce a forced win.
A number of early Microsoft programs had hidden animated stuffed animal characters which could be revealed by following a complicated sequence of inputs. An early version of Microsoft Excel contained a hidden Doom-like action game called “The Hall of Tortured Souls“.
Windows 3.1 has a hidden developer credits page, which can be accessed by following a sequence of right-clicking and entering code words which is passed around by word-of-mouth.
Two easter eggs exist in the “About” box of Adobe Photoshop 7: an alternative “Liquid Sky” splash screen and the ability to speed up credits to view funny quotations.
Easter eggs found in some Unix operating systems caused them to respond to the command “make love” with “not war?” and “why” with “why not” (a reference to The Prisoner in Berkeley Unix 1977).
The TOPS-10 operating system (for the DEC PDP-10 computer) had the “make love” hack before 1971; it included a short, thoughtful pause before the response. This same behavior occurred on the RSTS/E operating system where the command “make” was used to invoke the TECO editor, and TECO would also provide this response.
The largest Easter egg is purported to be in the Atari 400/800 version of Pitfall II: Lost Caverns, which contains an entire game that was more complex and challenging than the original Pitfall II.