In Nineteen Eighty Eight everything changed for our little group of players under my uncle's dungeon mastering. Our PC's were facing down & dying like flies in Realm's of Horror's version of S1 Tomb of Horrors. It was a savage & brutal lesson in death by party dynamics to learn.
Couple this with plot of S2 White Plume Mountain which we got deeply involved Your characters are trying to get back magical items stolen from their rightful owners and return them. This is because this isn't your usual dungeon traps and creatures are there as defenses for this stolen treasure! Our party died by the score back in '88 & '89. We learned not to take the game that seriously at all as well as not to get too attached to our PC's.
Then it was into the heart of S3 Expediation To The Barrier Peaks or at least S1-4 Realms of Horror version of it. My Uncle used the original module to pad out certain areas for full campaign play & more setting details.
Eventually we made it through to Realm of Horrors's version of s4 The Lost Caverns of Tsojcanth. And this was a long slog through the monsters, treasures, etc. of these modules & the one thing I can tell you about these versions of the classic Advanced Dungeons & Dragons modules as a dungeon master & player is to set up a town or city that is reachable as a home base for the PC's! Seriously it was a pain in the ass to try & outwit at every turn the minions of Drelnza, the vampiric daughter of long-deceased archmage Iggwilv. She was behind the scenes the entire time. Everything and the plot of Realms of Horror falls directly on her shoulders. "The PC's must investigate rumors of a lost treasure that scores of adventurers have perished attempting to find. The treasure is a remnant of the wealth amassed by the archmage Iggwilv, former ruler of Perrenland, prior to her presumed death at the hands of the demon Graz'zt, whom she had "imprisoned and forced into servitude." " Drelnza, the vampiric daughter of long-deceased archmage Iggwilv became a major enemy for our party of nine players over the course of a long three year stretch. To this day I loath her & her twisted family. My uncle would later before the end of the campaign tack onto T1 Temple of Elemental Evil. Why? Well I think that the Wiki entry for the The Lost Caverns of Tsojcanth reveals his diabolical plan involving Realms of Horror;
"The Lost Caverns of Tsojcanth is a revised and expanded version of The Lost Caverns of Tsojconth, a tournament adventure that Gygax wrote for WinterCon V, a gaming conventionsponsored by the Metro Detroit Gamers (MDG) in 1976. It is based in part on one of Rob Kuntz's dungeon levels, as Kuntz helped Gygax revise the tournament version. This original version consisted of eight loose sheets, an outer folder, and a zip-locked bag; only several hundred copies were printed. In the May 1980 issue of Dragon, Gygax said "Rob Kuntz has the reworked Lost Caverns module which must be finalized" and that "We want to get it into print as soon as possible." Lawrence Schick later suggested that "there's evidence that Gary considered Tsojcanth part of a longer Greyhawk campaign, placing the adventure between T1–T4 The Temple of Elemental Evil and WG4 The Forgotten Temple of Tharizdun. (By this reckoning, The Village of Hommlet, The Temple of Elemental Evil, and Tsojcanth are thus the "lost" WG1 through WG3 modules.) So, Tsojcanth was published in the S series because it got completed out of order, but was too good to delay.""
My uncle was playing with the fate of the Greyhawk setting dangling us like mice before the massive horror awaiting us as players in T1-4 Temple of Elemental Evil.
Realms of Horror is like a short hand version of all of the classic AD&D modules of yore Tomb of Horrors, White Plume Mountain, Expedition to the Barrier Peaks, and The Lost Caverns of Tsojcanth all laid out in a very nicely edited style. But these are not modules for the faint of heart nor those who are too attached to your PC's. With that in mind even though these modules have been edited together they are at their heart & soul brutal & dangerous as Lawrence Schick describes The Lost Caverns of Tsojcanth in his 1991 book Heroic Worlds, described the adventure as "A monster-filled labyrinth in the classic mode: kill 'em, rob 'em, and leave." I also think that this best describes Realms of Horror as well.