Castle Mistamere

The "Group Adventure" in the Mentzer Basic Dungeon Masters Rulebook was designed to be run by a beginning DM, for a group of beginning players:

"Many years ago, this part of the Realm of Man was ruled by a magic-user named Gygar, a man of great and mysterious powers.  He ruled the lands from his mighty Castle Mistamere, located at the foot of the mountains to the north.

"Gygar died after a long and peaceful rule, but no successor was named.  Over the years, the unclaimed castle fell into ruins.

“Now, centuries later, the outline of the broken towers can still be seen from the town, ever beckoning to seekers of danger, fame and fortune.

Frank Mentzer, DMs Rulebook (1983)

"The Realm of Man" may be a reference to "The Realm of mankind" mentioned in module B2 "The Keep on the Borderlands".

(We learn in the D&D Expert Set (1983) rulebook that Castle Mistamere is located in the Grand Duchy of Karameikos.)

I believe that Frank intended to honor both Gary Gygax and Dave Arneson, the co-creators of D&D, in coining the name Gygar, taking the first syllable of each of their surnames.

Map of Level One of Castle Mistamere, the "Group Adventure" from the D&D Basic Set (1983) DMs Rulebook, by Frank Mentzer

WotC posted a link to a pdf of the dungeon in 2008, as part of an article on Sample Dungeons by Bart Carroll, still available here (including 4e stats for Bargle).

OD&D Discussion forum member jeffb graciously shared pics of annotated maps in Mentzer's actual play copy of the DMs Rulebook, as part of a series of posts in June, 2020:

Map of Level Two of Castle Mistamere, including handwritten notations by Frank Mentzer, as originally posted by jeffb, here

Prospective DMs shouldn't be fooled - even though the "Group Adventure" is intended for beginning players, it can be deadly.

I've run it a couple of times, most recently several years ago for my kids, when my daughters first expressed interest in playing D&D (see our Campaign Journal).

Kill Bargle:

Mentzer provides general notes for Dungeon Levels Two and Three, used by Jason Bulmahn in "Kill Bargle", published in Dungeon #150 (September, 2007).

Bulmahn's version is for 3.5e, and was designed for four 3rd-level characters.  It's tough - and the difficulty ramps up pretty quickly.

I converted the adventure into BECMI, back when I ran it for my kids, and created a 7-page document in the style of the Basic Set rulebook, (downloadable here).

Tales of Mystara:

Check out the Solo Dungeon Crawler website for a well-done series of episodes involving an alternate expansion of the ruins of Castle Mistamere.

Update (Jan 11, 2024) - I recently came across this advice for adjudicating the magic bedroom in Polyhedron #24:

Q. In the revised Basic Set's group adventure, what happens if there are only two player characters and both fall asleep in Room 25?  (My players brought in three characters, but one died and the other two failed their Saving Throws in that room.)  Should I allow the players to try their Saving Throws again, or must I reduce the effect of the magic bedroom?

A. Modify the effect.  There are several ways to do it, but I'd recommend another Saving Throw each hour or so; if successful, the victim sleepwalks across the hall to Room 26.  (Note that if only one character makes the Saving Throw, he/she will soon awaken alone, and must find the other and figure out a remedy...)