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M2/MSOLO2 Maze of the Riddling Minotaur (Basic)

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An expert set solitaire adventure.

For a long time you have heard legends about the Island of Vacros; when you were only a child, the stories about evil minotaurs were used to scare you into behaving. Now you are grown, and you no longer believe children's stories.

But King Trueon of Cathos is worried: his daughter Princess Lydora has been kidnapped, and he has found clues that she has been taken to the ancient and evil island of Vacros. You have heard rumors that a large and dangerous mazework lies beneath the surface of the island - a mazework that is guarded by minotaurs. Of course many rumors are false, but then again ...

Product History

M2: "Maze of the Riddling Minotaur" (1983), by Jeff Grubb, is the second invisible-ink solo adventure for Basic D&D. It was published in July 1983.

About the Module Code. TSR would later call this adventure "MSOLO2" because of the publication of the Master-level adventure M2: "Vengeance of Alphaks" (1986). However, the adventure was never actually printed with that designation.

Sources: The Greek Myths. M2: "Maze of the Riddling Minotaur" (1983) is heavily based on Greek myths, as made obvious by the heavy use of Greek-sounding names. It's based on the story of Theseus and the minotaur: in it, Theseus (the SOLO player) is called upon by King Aegeus (King Trueon) to go to the island of Minos (Vacros) and slay the Minotaur (a monster). The silver owl the player is given to signal his failure both references a then-modern look at Greek myth, Clash of the Titans (1981), and recalls the black sails that were to report Theseus' death in the original story.

Origins (I): A New Designer. Jeff Grubb started playing Avalon Hill wargames in high school, but during his first year in college he wandered by a group of D&D players, and was told they needed a cleric. He soon began to GM his own campaign, set in the world of Toril; it would eventually influence both the Forgotten Realms and Krynn.

Grubb was volunteered to write the AD&D Open for Gen Con. In the end, he coordinated the whole tournament! After that, he applied for a job of TSR, but didn't get any traction until he stopped by the TSR Personnel Office in person, at which point Allen Hammack said to hire him. He began work in July 1982.

Grubb's first project for TSR was BH4: "Burned Bush Wells" (1983) for Boot Hill, but it appears that it was beaten to press by his second project, M2: "Maze of the Riddling Minotaur" (1983). Though TSR was almost a decade old when Grubb was designing "Maze", it was still a young company. Grubb recalls writing the adventure on a typewriter above the Dungeon Hobby Shop, because the Sheridian Springs Office wasn't ready yet and the company's computers were in high demand.

Origins (II): Spilling More Invisible Ink. Basic D&D's second solo adventure repeated the use of invisible ink and a special pen, following on M1: "Blizzard Pass" (1983). However, the line's invisible-ink pens was quite problematic.

That was partially a physical problem: the pens had to be velcroed to the outside of the modules. As a result, the modules wouldn't lie flat, and sometimes the pens would break the shrink wrap — often resulting in pens that were stolen or less.

The ink itself didn't work that well either. It meant that the adventure could only be run once. Worse, you could run out of ink while playing the adventure, either from overuse or non-use. Various reports also suggest that over time inked passages might fade or that uninked passages might appear, making the modules even more troublesome as artifacts. However, black (ultraviolet) light may be used to reveal the hidden information, even without a pen. The hidden text is also available on multiple web sites today.

The next Basic D&D Solo, XSOLO: "Lathan's Gold" (1984) would present all of its information in plain text. When Basic D&D returned to hidden text in CM5: "Mystery of the Snow Pearls" (1985), they would instead use a red-tinged "magic viewer". Obviously, the invisible ink technology was substandard, because when "Maze" was republished in German as ES2: "Im Rätsellabyrinth des Minotaurus", it used a magic viewer, not the invisible-ink pen.

Mapping Tropes. "Maze" features an invisible-ink map. Much of it is laid out in plain text, but various junctures, corridors, and rooms must instead be revealed with invisible ink.

Adventure Tropes: Choose Your Own Adventures. Rather than being a traditional "choose your own adventure" story, "Maze" is instead a location-based adventure. The player wanders across the map, revealing rooms. Only then does he go to the corresponding text.

"Maze" also includes diceless trap and combat systems. Whenever entering a new area, a player must reveal aa percentage to see if he detected any traps. In combat he similarly reveals boxes to see what armor class he hits and how much damage he does. He then applies that damage to a monster block which was previously hidden by invisible ink.

Exploring the Known World. This is one of the few Basic D&D adventures with no official (or even widely accepted) placement in the Known World. The Sea of Dread is, unsurprisingly, a favorite place for the adventure. However one of the favorite theories, by fan LoZompatore, uses "Maze" to fill a cartographic hole in the Known World by placing it amidst the Pearl Islands archipelago, with the islands of Vacros and Cathos replacing two islands that appear on some maps of the Known World, but not others. That nicely connects these Greek isles with the Roman-influenced Thyatis Empire.

Monsters of Note. The new monsters of "Maze" include a few fun variants of standard types including an obsidian golem, a pocket dragon, and a zombie-minotaur. A few of the "Maze" monsters even reappear in later Basic D&D "X" adventures.

As for non-zombified minotaurs: there are fewer than you'd expect. Changing up that expectation was one of the things that Grubb particularly liked about the module.

About the Designer: Grubb would soon move on to a dream project, the design of a whole new roleplaying game, Marvel Super Heroes (1984).

About the Product Historian

The history of this product was researched and written by Shannon Appelcline, the editor-in-chief of RPGnet and the author of Designers & Dragons — a history of the roleplaying industry told one company at a time. Please feel free to mail corrections, comments, and additions to

We (Wizards) recognize that some of the legacy content available on this website does not reflect the values of the Dungeons & Dragons franchise today. Some older content may reflect ethnic, racial, and gender prejudice that were commonplace in American society at that time. These depictions were wrong then and are wrong today. This content is presented as it was originally created, because to do otherwise would be the same as claiming these prejudices never existed. Dungeons & Dragons teaches that diversity is a strength, and we strive to make our D&D products as welcoming and inclusive as possible. This part of our work will never end.

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Discussions (4)
Customer avatar
Terry P April 22, 2017 4:10 pm UTC
It would be simple and nice to hide the sentences as for the magic viewer, no? I already own one from AD&D old adventure. I will definitely buy all the basic solo adventures: hope to see available soon Mystery of the snow pearl, Blizzard pass, Thunderdelve mountain and others.
Customer avatar
Douglas B April 11, 2017 3:47 pm UTC
The sample entries on p. 2 are not filled in.
Customer avatar
Terry P April 23, 2017 10:07 am UTC
Hope it will be corrected as soon as possible to buy a perfect filled and cleared from errors copy.
Customer avatar
Zia M April 30, 2017 2:07 am UTC
The sample entries are not necessary to run the adventure and were likely just joke text. Also, I don't think they obtained the text from the module itself. The filled in text is identical to the document mentioned in the history above that's been floating around the internet for years with the hidden text for this module. That also did not include the sample entries.

Just out of curiosity, if anyone owns a physical copy of this module and can still read what was in the sample boxes, it would be great if you could post them here.
Customer avatar
Heath B July 19, 2017 2:30 am UTC
I hope I'm allowed to do this. I just cracked open my physical copy for the first time in thirty years, and I can just barely still make out the hidden text on page 2. (Flipping through, it looks like I had a good time gaming; most of the entries are revealed.) If I'm seeing it correctly, here's the text:

X1. You enter the living room. Several people are watching television. The television is far too loud. Return to the example paragraph and choose again.
X2. You enter the den. Nobody is here, and the room is very quiet. You set your materials on the desk and begin to adventure in the [bold]Maze of the Riddling Minotaur.[/bold]
X3. You enter the kitchen. Two people are cooking dinner here. One of them explains, "We're busy in here, but I think the den is unoccupied." You may try the den (X2), or return to the example paragraph.
Customer avatar
Douglas B July 21, 2017 11:40 pm UTC
Thanks very much for transcribing these, Heath!
Customer avatar
William M April 11, 2017 2:13 pm UTC
I'm also curious about "hidden sections" in PDF and printed format and how these differ from the original. Thanks.
Customer avatar
Zia M April 11, 2017 3:28 pm UTC
The hidden sections are just filled in, there is no way to hide/unhide them. Would have been nice if they set the hidden font to the same color as the background and only made visible when highlighting.
Customer avatar
Douglas B April 11, 2017 3:49 pm UTC
Or just put the boxed entries on a separate layer, so users can turn them on or off.
Customer avatar
William M April 11, 2017 10:15 pm UTC
Thanks, I guess I'll still buy it, but I'll be extra strict with myself if I play it solo. :)
Customer avatar
William M April 11, 2017 10:16 pm UTC
Maybe they could revise the PDFs with that in mind. Nice idea.
Customer avatar
Andrew S April 11, 2017 2:03 pm UTC
Regarding POD, are entries that required a marker to reveal in the original version still obscured?
Customer avatar
Eric K April 23, 2021 4:26 am UTC
I’m also wondering this. From the preview it looks like this would be impossible to play because all the choices are blanked out.
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