1981 by TSR for the first edition of the Advanced Dungeons & Dragons rules, and consisted of a 32-page booklet with an outer folder. The module was written by David "Zeb" Cook, with cover art by Erol Otus and interior art by James Holloway, Jim Roslof, Harry Quinn, and Stephen D. Sullivan. Dwellers of the Forbidden City is the first of the mostly unrelated and unconnected Intermediate series (I-series) of modules designed for characters at between 4th and 8th levels. The module was originally intended to bear the code S4, but the code was reassigned to Lost Caverns of Tsojcanth before Dwellers was published. As published, the adventure bears the code I1. It was one of the first adventures written by Cook, and he attributed an early version of the module to his being hired at TSR. Cook would become the lead designer for the second edition of the AD&D rules, which debuted in 1989, and years later, he became the lead designer on the City of Villains MMORPG. The adventure was instrumental in introducing the yuan-ti as a new species of antagonists. Much like the drow from the Queen of the Spiders Series, the yuan-ti have been featured in a number of 1st, 2nd and 3rd Edition books for the D&D game, and are one of the few species that Wizards of the Coast did not keep open for the Open Game License. The yuan-ti have also been expanded from their introduction in this module to other game worlds, in particular the Forgotten Realms campaign setting. Other new monsters introduced to the game through this module include the aboleth, bullywug, mongrelman, tasloi, and yellow musk creeper. The module was set in the World of Greyhawk campaign setting, and was later used to add detail to the continent of Hepmonaland in Greyhawk supplements. In the Greyhawk accessory The Scarlet Brotherhood, by Sean K. Reynolds, the Forbidden City was named Xuxulieto, and the mountains wherein it lies are called the Xaro Mountains. Reception While Different Worlds described it as "a good buy", RPGnet gave it a slightly more favorable rating of nearly 6.8 ("Good"). Latter day D&D writer James Wyatt described it as the first "Super adventure", and lamented that with another hundred pages of fleshing out, it could have been as memorable as the landmark Temple of Elemental Evil. Gerry Klug reviewed The Dwellers of the Forbidden City in Ares