Back in the beginnings of Infocom, part of the issues with having games based on puzzles were that some people would run into difficulties with those puzzles. As a result, they’d mail questions to Infocom for help. Hints, if you wish, that would help them move on to the next puzzles. Lacking anything like an easily-accessible website to get information, people would rely on these questions and answers via mail. And there were a lot of them. Mike Dornbrook at Infocom was tasked with answering a lot of these questions in the beginning of the company’s history (others helped as well) and eventually decided it would be a much smarter idea to create a pre-packaged collection of questions and answers for the games, which could then be sold as products, along with maps and t-shirts and anything else Infocom/Zork related.
A problem presented itself, though: people would only want a slight hint, a nudge in the right direction. They didn’t want to be handed the whole answer and they certainly didn’t want a pre-printed list of all the answers right there either tempting or distracting them. Some research and thought went into this problem.
The solution that Infocom came up with were Invisiclues, which were booklets printed in invisible ink. You could see questions but you couldn’t see the answers. To see the answers, there was a special pen that came with the booklet, and as you needed help, you would rub the pen in a box and a hint would appear. There were a few boxes under each question, and from that you could slowly work up from a slight nudge to being handed the answer outright.
From the excellent infocom.elsewhere.org site, here’s an example of how this looked. (Don’t worry, it’s a page that has a meaningless example and no actual hints):
If you’re wondering about what would happen if you read all the questions and got ideas from them, Infocom thought that through too – a portion of the questions would be answers to problems not in the game, and would ridicule you for trying to cheat. There was always, throughout the construction of these, an attempt to balance the need to know with the desire to come up with the final solution on your own, which was (after all) the whole point of playing these games.
The process of these Invisiclues is interesting. At the time this was utilized (the early 1980s) the term for them was “latent image printing”, and referred to images that were printed but required additional chemicals or processes to be found. In this case, the chemicals in the pen (which had a yellowish tint) would activate the chemicals in the printed text and cause that text to become visible. It is all explained not-very-clearly in this patent, in case you want to whip up a batch for yourself.
Speaking of which….
One of the concerns with my documentary is that it reveals the solutions to games in the course of interviews. I definitely don’t want people watching this film to be exposed to solutions of games they’ve just gotten excited about while watching my documentary. How lame would that be? So I’ve been considering ways to get around this problem.
One possibility, which I may do, is a selection from the menu on a DVD so there’s a spoiler and non-spoiler version of the movie. But the other… is invisiclues!
Besides allowing people the fun of what Invisiclues used to be like, they would serve a purpose, allowing people to unearth some hints about what people were talking about without dropping the total answer.. unless they wanted to hear it. It just strikes me as a fun idea.
The problem, though, is I have had an enormously hard time finding anyone who does it. If you have any idea, please write to me or comment below. Bear in mind, I spent a lot of time on this a while back, so here is what I know:
- The place that probably makes the most of these types of book/pen combinations is Lee Publications. They have a wide range of books and even license very up to date properties to make books out of them. I can find absolutely no evidence that they would do an outside contract for someone to print, say, 5000 of these booklets. Maybe you can find a way?
- With access to internal Infocom documents, I believe I have found the name of the company that did the original printing back in the 1980s. It seems to have been A.B. Dick company that made the “A.B. Dick Latent Image Pens”. Communication happens between them and American Printers and Lithographers over whether the pens are poisionous (they weren’t). American might have made the actual books themselves using A.B. Dick products. Both these companies were in Chicago. It’s been a bunch of years since then and I can find no evidence that either of these companies do this anymore.
- It appears that several governments (NY and Federal) have tried to acquire these pens and paper for testing. Here’s a particularly dull example of that request. I find no indication they ever got them.
- Possibly, just possibly, what used to be “latent image” printing is now under the header of “security printing”.
So I am not so much at a dead end but in a situation where I haven’t had time to track stuff down further. My suspicion is a lot of the really complicated jobs have moved to China, but that in fact may mean I just have to find the right US company that deals with China. Would you like to help?
Find out how I can do this, and you’ll get a credit in the movie.
Update: Dennis Jerz has put me in contact with Lee Publications and things looks like a deal might be worked out. Thanks a ton, Dennis!