This material was originally published as two separate modules, D1 (DESCENT INTO THE DEPTHS OF THE EARTH) and D2 (SHRINE OF THE KUO-TOA).
Contained herein are referee notes, background information, maps, and exploration keys intended for use with the ADVANCED DUNGEONS & DRAGONS rules.
The module can be used alone or as part of an extended adventure that begins with Dungeon Module G-1-2-3 (AGAINST THE GIANTS) and continues with modules D3 (THE VAULT OF THE DROW) and Q1 (QUEEN OF THE DEMONWEB PITS).
The cover of this module is one of my very favorites - this was one of my first modules that I owned and the mystery of it was enticing. It stands well in the test of time in my eyes.
Additional comments after re-reading in 2018:
The cover art is my very favorite. I love the mixtures of blue and green, and the horrifying picture on the back is full of everything that Dungeons and Dragons was to me when I was playing as a kid. The mystery of what a Mind Flayer is and what they do. I love almost every picture in this module, as it is so evocative.
I remember setting up a snow cave (as a kid) in my back yard and attempting to run this module - crazy.
The framework of this module is just that, a framework. There is much to be done with this module by a creative Dungeon Master.
I didn't enjoy this one as much as the ones from the Giant series. Or maybe it suffers from the dryness of the first module, which I think was the same issue I had with G1.
To be fair, D2 is better than D1, as in you get to see some fun and bizarre stuff, and I feel like there's a better unity between each parts of the module than in D1. The Kuo-Toa's territory, with the Sea Mother shrine and everything was great for inspiration regarding tribes that would use their beliefs as somewhat of a mandatory ritual for passerby. I also really liked the lone Kuo-Toa ferryman at the river. I wish the insanity of the Kuo-Toa was explored a bit more in regards to the tribe and how it's dealt with by the monitors.
Other than these two parts, the rest was a bit meh. I did enjoy reading about the Kuo-Toa and the Deep Gnomes at the end of the module, and to see how things were back then regarding these races and their abilities.
The lack of women, even in the more "drow focused" parts were not unnoticed, but hey, sadly expected.
This compilation of D1 and D2 adds a few new pieces of art and the tournament characters. Overall, my impression of this module is that thematically, Gary has captured the wonder of Jules Verne's Journey to the Center of the Earth, but in actual play I think it would feel like a lot of mass combats that are just "on the way" to the main adventure, which is D3. For a combat-heavy group that can devote long frequent sessions to running this, it could work. These days, where most of us old fogies play once a month for a few hours, it would be interminable, unless the party goes "off the grid" and the DM gets really inventive with the underdark politics.
It was so good to read this again, some 40 years after I first DMd it. The compiled D1-2 takes the original 1978 monochrome modules and puts them together in a 1981 publication with some sublime art, not least the Roslof and Willingham covers. They are classic modules but are probably the weaker of the GDQ Series in that they are very much descriptions of setting. I mean, they are great settings, but lack a real plot or story. Depending on how G1_3 ended it may be a pursuit or an exploration or trying to discover more about the Drow. D1 has a couple of encounters, some random tables, and then a massive cave network with some fun encounters including a lich! The place has some drow and could be visualised as a drow merchant station the PCs have to get past, or take the opportunity to grab prisoners, or just treasure hunt. D2 is much better, and lots of detail of the (new at the time) Kuo-Toa is given. The shrine is enormous, and rammed with enemies and a murder hobo approach would invite death. With some great details to the shrine it's begging for a reason to sneak around, which isn't really given. It's on the path of the drow (whether merchants or the agitators from G3) but the PCs could just divert around. Indeed, with mentions of how the Kuo-Toa hate the drow it feels odd to have this en-route. So in essence it needs some work to flesh out and realise potential, especially for D2 which is really well described. There's no doubt nostalgia gives it an extra shine, but in its era this was a great addition to the range, and a very evocative setting.
This is really just okay. I get that a lot of people have a nostalgic love of it, and rightly so. I do too. But the whole start of the adventure is very boring. In fact, it doesn't pick up until the very end where it actually gets great.