One of my top three favorite modules of all time is undoubtedly The Hidden Shrine of Tamoachan by Harold Johnson & Jeff R. Leason.
It's one of the first, if not the first, tournament module ever published as such (although it's worth noting that many famous modules—among them The Tomb of Horrors—first saw life in convention tournaments).
Despite its age, the module somehow blends many diverse concepts into a united whole and it also eschews the wild unrealism of White Plume Mountain and The Ghost Tower of Inverness while still offering an intense array of unique challenges.
Theme rules here. The adventure takes place in a pyramid with a heavy Aztec/Mayan flavor. The encounter areas are very detailed, almost over-detailed, and all the treasures and most monsters are tailored to fit the setting. This leads to some unique critters, such as a mummy-centaur. The setting is utterly immersive.
I always loved settings that transport you—not always literally—to a new place. The PCs should never feel like they can simply lean out the cave door into the sunlight whenever they please, the way I see it. That's why I like the Tomb of Horrors ... once the PCs enter, they soon have the feeling that there's no turning back until the ultimate goal is reached. I love that. This module does you one better, if played one way (there are two, to be mentioned later) the PCs are forced to travel upward in their bid to escape the pyramid ruins before poison gas lays them low. Yes, it's a bit railroady, but the creativity employed in the encounters and the multiple paths to freedom give the ziggurat a surprisingly unconstrained feel.
Name has a great balance of traps, critters, and puzzles. My own creations are fairly puzzle-light, but when reading works like this I'm galvanized to enrich my own settings with more puzzles the players can solve. Here they are such a crucial part of this adventure that players failing to think on their feet might well kiss their PCs goodbye.
3. Background Detail
The author here has done his research, and it shows. This dungeon wasn't designed or written in a week or two, I'll wager. I reads like a labor or love (as the best adventures do).
4. Cool NPCs
The module provides three tourney-ready PCs that fit well with the overall theme. A pity there wasn't a few more!
The pyramid may be entered from the bottom—in the tournament-style start the PCs are running away from bounty hunters in the jungle and are dumped into the pyramid's basement by a cave-in—or it may be entered from the top down by more exploration-minded parties. Thus, some rooms are detailed to be run from varying directions.
This author ploy succeeds in part, but IMHO the dungeon works much better if the PCs climb upwards because some traps and secret doors simply are oriented that way, and the pyramid encounters also seem to get more difficult as one ascends.
6. Cool Encounters
The encounters, as mentioned, are varied and all show creativity. There is a chamber where something with molten feet has leapt about and melted huge, clawed footprints into the floor. But where is the creature? Another area requires the characters to traverse a pit via jungle-gym style bars while killer plants hurl thorns at them. Yet another area forces inquisitive PCs into a game of pelota (in this case, a sort of Mayan soccer) where they must knock an dangerous animated ball into a goal or risk setting off a deadly trap.
Let's see. A room that fills with sand—check. A room decorated with magical mirrors—check. Huge mill stones tumbling Indiana Jones-style down stairways—check. Creepy undead and entombed vampires—check. There's even a distinct nod to Metamorphosis Alpha in one room. This one has it all.
The module shows its age in some respects. I spent much of my flight to the last Gen Con reading this module in the hopes of running it for the Goodman Games crew (alas, this didn't come to pass) and I was struck by the huge blocks of detail-heavy text the DM must wade through at times. A DM grabbing this off the shelf isn't going to run it well on the fly. Indeed, any DM thinking about running this should set aside a decent chunk of time to read it properly and understand all the encounters and puzzles. That said, I think the DM will find the investment well spend indeed.
I highly recommend this module. It may not be classic as far as having orcs and the like, but it more than makes up for that by pushing its chosen setting to the limits.