If C1: Hidden Shrine of Tamoachan has similarities with S1: Tomb of Horrors, C2: The Ghost Tower of Inverness has some clear parallels with S2: White Plume Mountain. Both were originally set in homebrew campaign worlds before being transplanted to Greyhawk upon publication with TSR. Both make use of the fun house approach, collecting a number of weird encounters rather than attempting to create an ecology that makes some kind of realistic sense. No cursed artifact weapons here, though.

Like Hidden Shrine, this was originally a tournament module (run at Wintercon VIII in 1979) and the “green cover” first edition was a loose leaf version printed in a short run primarily for convention goers. It has since become one of those crown jewels for collectors thanks partly to its rarity and, I think, primarily because it has a bunch of Erol Otus illustrations that were not reprinted in the second edition.

I prefer the fine tuned atmosphere of Hidden Shrine over Inverness – my brain is hardwired to enjoy realistic ecologies and the fun house modules always feel all over the place to me. Plus there is time travel. On the other hand, there is a pretty great chess-based puzzle (maybe the first for D&D, but definitely not the last) and I feel like the frozen bugbear room has a bit of a classic rep.

Lots of great old school art. The Roslof cover is pretty great and Dee’s fire giant on the back is a fave. Lots of umber hulks, too – both Otus and Dee deliver one and I truly believe you can’t have too many umber hulks.