I posted this on reddit some time ago, but wanted to repost to the blog for completeness.

Thoughts on Hidden Shrine of Tamoachan

I ran this a month or so ago, as extra content on ToA, and wanted to give some thoughts for any DMs who want to run it.

General Lore

The general lore is pretty cool, but in the 5e module it gets very short shrift in explaining what is going on, the whole thing is very much show, don;t tell, to the point that the players may not get what is going on. You will need to find a way to integrate how this place ended up wherever you put it, and how the god the shrine was devoted to fits into the 5e setting. Or you could name swap or something. Here is a cool, very old, take on it that can help you get your creative juices flowing:

http://www.devinlc.com/scenariotamoachan.htm

Specific Lore Issues

Most likely, no one in your party will speak or read the languages the tomb has in it. So… plan accordingly if you want to play up the lore within the module. Next, The top two tiers are kind of a mess. There are a lot of events that either have no explanation, or break with 5e concepts. The biggest example being the evil guardian naga in area 42. That is a contradiction in terms in 5e.

Also of concern is who/what is stocking this place with the foes, and why do they stay there? If your players are like mine, and talked through a few encounters, get ready to have plausible answers that the module does not give. Beyond that the whole top two floors are kind of weird to explain if no one has any context, and the enemies seem kind of out of nowhere. I ended up doing a deep dive into who Zotzilaha is, and came up with a reason for the temple to be in Faerun (spellplague issues).

Mechanics Thoughts

The fog prevents a party from taking any rests in the bottom two levels. Use this, and make it clear.
The very first room could take a whole session. Think through how you want to handle it ahead of time. No right answers, just a prep thought.
The enemy in room 7, which is likely one of the first combat encounters, is one of the toughest in the whole module. The item that enemy drops is also crazy. Read up on the weapon and all the effects it has, and decide if you want that in your game.
Room 23 and 23A makes very little sense (there is no lore point for it) and has very easy TPK in it. I took it out. Read it and understand it if you want to run it.
The stone block, at area 21, if it is pushed all the way up to area 26, still completely blocks the path. Like area 23, this is a gothcha moment. Creative players can solve this, but pushing it up the ramp is a red herring. Area 29, you may want to change the way it works to make it more fun.
Room 35 is another easy way to kill many players between the radiant pool and the creature in the ceiling.
Area 42 seems to just be a dick-move room for a great many reasons, as the whole thing is built on a lie, and a monster breaking the canonical approach to what that monster is.
Room 44 can easily one-shot a player, depending on various factors. Maybe put a mangled corpse in to show something is up.

Overall, if you want some in depth alternate takes on some of the above rooms, check out this blog:

https://chaoticneutraldm.com/2019/04/25/hidden-shrine-of-tamoachan/

General Thoughts:

I like this module on the whole, I just thing it needs a serious working over for many parties. It has some really cool set pieces (areas 3, 11, 13, 27, 30, 32/32 and 45 are all wonderful). It also has some real pitfalls (language barrier, a handful of gotcha traps, the lore inconsistencies, and fitting it in to your game world). The original version was meant to use tournament scoring rules, which is a totally different way to play the game.

I threw out the top to tiers for a few reasons and made a new map where a resurrected version of the enemy in area 7 came back. I am not saying you MUST do this, but you may want to consider putting a bigger bad at the end to properly cap off the the whole experience. Have fun!