In computing, the word is sometimes used as a metasyntactic variable or as a video game cheat code, the canonical "magic word". In mathematics, the word is used as a mnemonic for the cross product.
Modern usage derives primarily from one of the earliest computer games, Colossal Cave Adventure, in which the idea is to explore an underground cave with many rooms, collecting the treasures found there. By typing "xyzzy" at the appropriate time, the player could move instantly between two otherwise distant points. As Colossal Cave Adventure was both the first adventure game and the first interactive fiction, hundreds of later interactive fiction games included responses to the command "xyzzy" in tribute.
The origin of the word has been the subject of debate. Rick Adams pointed out that the mnemonic "XYZZY" has long been taught by math teachers to remember the process for performing cross products (as a mnemonic that lists the order of subscripts to be multiplied first). Crowther, author of Colossal Cave Adventure, states that he was unaware of the mnemonic, and that he "made it up from whole cloth" when writing the game.
Xyzzy has been implemented as an undocumented no-op command on several operating systems; in Data General's AOS, for example, it would typically respond "Nothing happens", just as the game did if the magic was invoked at the wrong spot or before a player had performed the action that enabled the word. The 32-bit version, AOS/VS, would respond "Twice as much happens". On several computer systems from Sun Microsystems, the command "xyzzy" is used to enter the interactive shell of the u-boot bootloader. Early versions of Zenith Z-DOS (a re-branded variant of MS-DOS 1.25) had the command "xyzzy" which took a parameter of "on" or "off". Xyzzy by itself would print the status of the last "xyzzy on" or "xyzzy off" command.
The popular Minesweeper game under older versions of Microsoft Windows had a cheat mode triggered by entering the comment xyzzy, then pressing the key sequence shift and then enter, which turned a single pixel in the top-left corner of the entire screen into a small black or white dot depending on whether or not the mouse pointer is over a mine. This easter egg was present in all Windows versions through Windows XP Service Pack 2, but under Windows 95, 98 and NT 4.0 the pixel was visible only if the standard Explorer desktop was not running. The easter egg does not exist in versions after Windows XP SP3.
The low-traffic Usenet newsgroup alt.xyzzy is used for test messages, to which other readers (if there are any) customarily respond, "Nothing happens" as a note that the test message was successfully received. In the Internet Relay Chat client mIRC and Pidgin, entering the undocumented command "/xyzzy" will display the response "Nothing happens". The string "xyzzy" is also used internally by mIRC as the hard-coded master encryption key that is used to decrypt over 20 sensitive strings from within the mirc.exe program file.
A "deluxe chatting program" for DIGITAL's VAX/VMS written by David Bolen in 1987 and distributed via BITNET took the name xyzzy. It enabled users on the same system or on linked DECnet nodes to communicate via text in real time. There was a compatible program with the same name for IBM's VM/CMS.
xYzZY is used as the default boundary marker by the Perl HTTP::Message module for multipart MIME messages, and was used in Apple's AtEase for workgroups as the default administrator password in the 1990s.
In the game Zork, typing xyzzy and pressing enter produces the response: A hollow voice says "fool." The command commonly produces a humorous response in other Infocom games and text adventures, leading to its usage in the title of the interactive fiction competition, the XYZZY Awards.
In Dungeons and Dragons Online, Xy'zzy is the nigh-invulnerable raid boss in the Hound of Xoriat adventure.
In Primordia, one is able to get a bonus short scene featuring a shout-out to 'CCA' as a form of non-playable text-adventure, which is accessible by typing 'xyzzy' in Memorious's data-kiosk.
- xyzzy in the Jargon File.
- Rick Adams. "Everything you ever wanted to know about…the magic word XYZZY". The Colossal Cave Adventure page.
- David Welbourn. "xyzzy responses". A web page giving responses to "xyzzy" in many games of interactive fiction
- Dennis G. Jerz. "Somewhere Nearby is Colossal Cave: Examining Will Crowther's Original "Adventure" in Code and in Kentucky".
- "Page 17" (PDF). Retrieved 2009-08-20.
- eeggs.com. "Windows 2000 Easter Eggs - Eeggs.com". Eeggs.com<!. Retrieved 2009-08-20.
- "Minesweeper Cheat codes".
- "Pidgin source code repository". "See gtkconv.c"
- "mIRC - Encrypted internal strings".
- David Bolen (August 24, 1989). "VAX/VMS XYZZY Reference Card".
- Sean M. Burke (2002). "Perl and LWP", p.82. O'Reilly Media, Inc. ISBN 0-596-00178-9
- Wells, Brad. "How I cracked the Cr-48 Easter Egg". Retrieved 13 June 2011.
- "Road Rash Cheats - IGN".