Viewing old hintbooks without a red gel viewer
I’ve recently been re-playing “Indiana Jones and the Last Crusade”, and it’s been long enough since the last time that I’ve needed to re-consult the hintbook a couple times.
Lemme back up.
Adventure games had hintbooks?
First, by “adventure game”, I specifically mean point-and-click graphical adventure games like “Last Crusade”.
Hi, I’m Indiana Jones. Welcome to my game.
Early adventure games had a raft of verbs for specifying what you wanted your character to do—early Lucasfilm/LucasArts games like “Last Crusade” had over a dozen, and early Sierra games had command-line input with too many verbs to list. As the form matured, games dispensed with the specific verbs in favor of contextual “use” and “examine” actions on the left and right mouse button, respectively, but the essence remains the same: exploration and puzzle-solving to progress a narrative.
And some of those puzzles could be tricky, so one thing that publishers like LucasArts either included in the box or sold as an add-on was hintbooks.
Photo “borrowed” in true adventure-game-protagonist style from this eBay listing. All this can be yours for only $385!
Typically, a hintbook included a series of questions you might ask, like “how do I get ye flask”, with one or more hints after each question, each one more spoilery than the last, and each one veiled in some way so you could get a little closer to figuring out the solution without having it just dropped on you right away.
How hintbooks worked
The exact mechanism varied. Infocom was famous for their “InvisiClues” which involved disappearing ink that reappeared with a special marker pen. But Lucasfilm/LucasArts—and one or two other publishers, including Sierra—used a different system involving a red gel viewer.
“Gel” in this case is the photographic term: a sheet of translucent plastic that filters out all colors except one. A red gel passes red light but blocks all other colors. If you’ve ever seen a pair of red-and-blue 3D glasses, those are red and blue gels—and, in fact, you could use the red side of such glasses if you lost the viewer that came with the hintbook.
The text in the books was printed in color. Question headings and the actual hints were printed in cyan, but the veil over the hints was made of red text, or a noise pattern in red and orange.
Viewing preserved hintbooks
Many if not all of these hintbooks have been preserved online, thanks to tenacious collectors, but reading them can be a challenge. Some of have had the hints unveiled for you, which is for the best for the invisible-ink ones (and I’m sure was no small feat).
For red-gel hintbooks, it actually is possible to replicate the red gel viewer in software, given sufficiently high-quality scans of the pages.
I use Affinity Photo (a pre-Canva version). You could use Photoshop or maybe even Acorn.
At minimum, you need a Color Matrix* filter (called something else in some apps—Affinity Photo calls it Channel Mixer) and something that can convert the fairly murky result of that into a more-readable black-and-white, such as a Threshold filter. Ideally, you could mask these filters to a particular shape; Affinity has this ability (you can put the filters in a group, with the scanned page outside of and below the group, and apply a rectangular mask to the group).
For the “Last Crusade” hintbook, I had success with red=red × 100%, green=red × 100% + green × 100%, blue=red × 100%, and a threshold of 92%. No need to mess with the alpha.
With a document so constructed, you can drop in a scanned page, layer it underneath the group, and then drag the mask shape around to use as your “viewer”.
Now you can read those hintbooks just like in the 1990s, except you’ll never have to worry about losing the hintbook viewer gizmo again.
I’m here to chew bubblegum and punch Nazis. And I’m all out of bubblegum.
The tricky bit: Getting usable scans
I was going to include a list of links to hintbooks you can try this with, but apparently I got lucky with the Indiana Jones and the Last Crusade hintbook being a usable scan. The others I looked at all have the colors messed with (probably on some blanket preset that makes sense for B&W documents) in such a way that the trick no longer works.
Please, if you scan in a hintbook that requires a red gel viewer, publish the scans without color-correction.
Apparently, later LucasArts games—including the other Indy adventure, “Fate of Atlantis”—ditched the red gel trick entirely in their hintbooks, and those are of course perfectly readable today.
Bonus link
While looking for a photo of the sort of viewer I’m talking about, I came across this tutorial for making your own red gel viewer. I haven’t tried it, but if you really want to do things the old-school way, and don’t want to try your luck finding a vintage one on eBay, that might be an option.