It's great to be 40 years into the hobby and read modules that I never had chance (or money) to back in the day. Oddly I recall C2 now being one of the first modules I physically saw around a friend's house whose older brothers played DnD. The elemental layers were the ones I recognise from the card cover, although at the time (1982) it meant little to me.
C2 is similar to S2 in the fact it's a so-called 'funhouse' dungeon. The rooms contained within have no purpose other than to injure, delay, or impair the characters. There's a flimsy 'out of time' narrative to justify this, and some background shoe-horning it into Greyhawk (the default setting of AD&D at the time). This is forgivable as the adventure is good fun. Essentially the dungeon level is based around four routes into the dungeon towards a central chamber unlocked by pieces of a 'key' that the PCs collect.
Once through the challenge to get the keys, which include bugbears frozen in time, a chess room, pop up monsters, an umber hulk, and a manticore, they then access the upper tower levels. Each of these is a huge room based on an element, with a cool use of mass reverse gravity in one. The final room is a brutal almost computer game -like dodge and rush to grab a Soul Gem before it drains all your magic items or indeed your soul. Although at the start it says the adventure isn't just combat, there's not a vast amount of problem solving or traps to get past.
The module was designed for tournaments (C is 'competition') and was originally played 1979 and released 1980. Theres a fair amount of stuff for tournament play-- 5 pre-gen PCs of level 7to10, a big equipment list and budget for the team, and a bespoke introduction in which most of the PCs are criminals and being sent by the Duke of Urnst and his wizard Seer into the deadly ruined tower (I'm assuming the Ghost in Ghost Tower refers more to the spectral out of time nature of the ruined tower versus any actual undead, of which there's none). A scoring system is provided, a time limit of 3h (which given the speed of some combats is tight), and rooms relevant to tournament Vs non-tournament play clearly labelled.
Finally, the art is great-- most of the early greats are here: Jeff Dee, Erol Otus, Jim Roslof, David Laforce, and a great medusa by Willingham. My personal favourite is Dee's umber hulk (page 9) which I'm sure I've seen elsewhere. Just great. The cover is cool, but nothing to do with the actual adventure, and Dee's Fire Giant with rainbow sword on the back cover is awesome- should have been the front!
Overall, a fun throwaway dungeon which might seem a little vanilla to modern tastes but would have ticked the boxes for my teenage DM brain.