# InvisiClues > Mediated Wiki article. Canonical URL: https://mediated.wiki/source/InvisiClues > Markdown URL: https://mediated.wiki/source/InvisiClues.md > Source: https://en.wikipedia.org/wiki/InvisiClues > Source revision: 1226332536 > License: Creative Commons Attribution-ShareAlike 4.0 International (https://creativecommons.org/licenses/by-sa/4.0/) **InvisiClues** were hint [booklets](/source/Book) sold by [Infocom](/source/Infocom) to help players solve [puzzles](/source/Puzzle) in their [interactive fiction](/source/Interactive_fiction) [computer games](/source/Computer_game).[1] Before Infocom's games exploded in popularity, players could request hints by mail and receive a type-written sheet in response. When the number of requests proved unmanageable, the Zork Users Group began a pay-per-hint telephone system. The invention of InvisiClues replaced this system and was revolutionary: a player could often buy a hint book at the same time and at the same location as the game itself. Questions relating to the game were printed in the book, for example, the InvisiClues for *[Zork I](/source/Zork_I)*[2] contained the question "How can I kill the songbird?"[3] A series of "empty" boxes located below or following the text contained the answers, printed in [invisible ink](/source/Invisible_ink). The contents of each box could be revealed by using a highlighter-like marker that came with the book.[1] Over time, the ink degraded and the text reverted to invisibility. To discourage players from accidentally learning what awaited by reading all the questions, each booklet contained a number of plausible-sounding "fake" questions. Revealing these answers usually resulted in a mild scolding. Several "non-puzzles" also had questions, such as the songbird example used above. The answer to these was usually a tersely-worded statement saying "You can't do that", often followed by one or more items reading "[This space intentionally left blank](/source/Intentionally_blank_page)" or, on occasion, showed false clues such as "How Do I get off the roof of the House?" the clue being "How did you get up there?". Even the answers to real questions began with vague hints, so a player could choose to stop short of getting explicit solutions to the puzzles. The InvisiClues books were very popular. By late 1984 Infocom had sold more than 500,000 copies at $9.95 each for its games, including about 200,000 for the *Zork I* book. [Richard E. Snyder](/source/Richard_E._Snyder) of [Simon & Schuster](/source/Simon_%26_Schuster) amazed InvisiClues author Mike Dornbrook by stating that such volumes made him "one of the bestselling authors on the planet ... In terms of dollars you're at [Stephen King](/source/Stephen_King) level!"[4] For a short time, *The Status Line*, the Infocom Game newsletter, included "**Visiclues**". These were just select InvisiClues questions from a couple of newer games, with answers written in a simple [cryptogram](/source/Cryptogram). InvisiClues books were almost always packaged with the navigation map for the same given game. Though InvisiClues, like the games themselves, are no longer available, a few [Internet](/source/Internet) sites have recreated the booklets. Typically, either all the answers are printed normally on the site or the user must "highlight" a section by clicking and dragging the mouse to reveal the hints. The InvisiClues were included in a hint booklet packaged with *[The Lost Treasures of Infocom](/source/The_Lost_Treasures_of_Infocom)*. However, the InvisiClues packaged with the *Treasures* were not produced to Infocom's high standards: - The clues were not written in invisible ink, which made it easy to accidentally get answers to puzzles. - Some of the hints were missing - There were many errors, such as misspellings, mis-capitalizations, formatting issues, and punctuation errors. The clues were not included with *The Lost Treasures of Infocom II*. However, there was a pay-per-minute card included. In the Solid Gold line, typing "HINT" twice would allow you to access Invisiclues from in-game. ## See also - [Decoder pen](/source/Decoder_pen) - [Sierra Entertainment](/source/Sierra_Entertainment) sold similar "hint books" for their titles using the [decoder pen](/source/Decoder_pen) concept. ## References 1. [InvisiClues Introduction](http://www.csd.uwo.ca/Infocom/Invisiclues/intro.html) [Archived](https://web.archive.org/web/20090713054632/http://www.csd.uwo.ca/Infocom/Invisiclues/intro.html) 2009-07-13 at the Wayback Machine from the Infocom Homepage (hosted by [The University of Western Ontario](/source/The_University_of_Western_Ontario)) 1. [InvisiClues for *Zork I*](http://www.csd.uwo.ca/Infocom/Invisiclues/zork1/) [Archived](https://web.archive.org/web/20090101183745/http://www.csd.uwo.ca/Infocom/Invisiclues/zork1/) 2009-01-01 at the Wayback Machine from the Infocom Homepage 1. ["How can I kill the songbird?" question](http://www.csd.uwo.ca/Infocom/Invisiclues/zork1/chapter1/AboveGround2/) [Archived](https://web.archive.org/web/20060112034256/http://www.csd.uwo.ca/Infocom/Invisiclues/zork1/chapter1/AboveGround2/) 2006-01-12 at the Wayback Machine from the InvisiClues page from the Infocom Homepage 1. Maher, Jimmy (2013-10-23). ["Masters of the Game"](http://www.filfre.net/2013/10/23/). The Digital Antiquarian. Retrieved 9 January 2015. ## External links - [The Infocom Gallery](http://gallery.guetech.org/invisiclues.html), a site with InvisiClues to some Infocom games --- Adapted from the Wikipedia article [InvisiClues](https://en.wikipedia.org/wiki/InvisiClues) by Wikipedia contributors ([contributor history](https://en.wikipedia.org/wiki/InvisiClues?action=history)). Available under [Creative Commons Attribution-ShareAlike 4.0 International](https://creativecommons.org/licenses/by-sa/4.0/). Changes may have been made.