Ptolus is a coastal city at the edge of the Tarsis empire that is set on the water planet Praemal, which is itself currently experiencing an ice age.
Each chapter, organized like a tour book, provides information about each area of the city, with details of notable characters, rumors, and adventure hooks.
[1] Ptolus also provides a series of linked adventures that inevitably lead to a confrontation with the evil entity that inhabits the mysterious spire.
[3] In addition to the city map and 24 loose playing aids, the book comes with a CD-ROM that contains another adventure, The Night of Dissolution, as well as two other Malhavoc publications that can be used in the Ptolus setting, The Banewarrens and Chaositech.
In the late 1990s, while Monte Cook worked at Wizards of the Coast (WotC), he and several other members of the staff, including Andy Collins, Bruce R. Cordell, and Sean K. Reynolds played a home campaign of Advanced Dungeons & Dragons using the 2nd edition set of rules.
Not wanting to oversee the actual details of publication, Cook used White Wolf Publishing's "Sword & Sorcery" imprint to release his third-party D&D material.
[4] Using this publication stream, Cook produced several books, the last and largest[4] being Ptolus: City of the Spire, featuring cover art by Todd Lockwood, interior illustrations by Toren Atkinson, Kevin Crossley, Pawel Dobosz, Talon Cole Dunning, Jason Engle, Michael Komarck, Brian J. LeBlanc, Eric M. Lofgren, Howard Lyon, Michael Phillippi, Alan Pollack, Randall K. Post, Peter Schlough, JD Sparks, Arnie Swekel, Sam Wood, Kieran J. Yanner, and Maciej Zagórski, and cartography by Edward Bourelle.
[3] In February 2020, Monte Cook Games launched crowd funding to successfully bring back Ptolus for 5th Edition D&D and Cypher System.
[5] In Issue 130 of Inquest Gamer, Brent Fishbaugh noted "At $119.99 and 672 pages, Ptolus: Monte Cook's City by the Spire for d20 fantasy promises to be everything you could ever want in a roleplaying setting."
Fishbaugh thought one of the best things was that "this is a look inside the heads of D&D designers, and that alone is worth the price of admission; this is the original campaign setting creators used to playtest when constructing the Third Edition rules."