Gen Con XIII was held in August, 1980 on the Parkside Campus of the University of Wisconsin. The AD&D open tournament was "Against the Slavers", a collaborative effort by David “Zeb” Cook, Harold Johnson, Tom Moldvay, Allen Hammack, and Lawrence Schick.
Gen Con XIII as advertised in The Dragon #40 (August, 1980).
According to Jake Jaquet's article "Conventions 1980" published in The Dragon #43, the tournament started with over 800 players (a sizeable proportion of the 4500 in attendance). In a separate article, Dave Cook describes how such a large number of players was handled:
Five first rounds were required to narrow the contestants down to a mere 135 semi-finalists which in turn became only 45 finalists. To do all this required 5 different first-round scenarios, a semi-final round, and a final-round design.
Dave Cook, "Survival tips for the Slave Pits" The Dragon #43
There are two corrections to be made on the map of A1, both of which should be obvious to those DMs who have already read the module. The first is in the upper section (temple) at area 16. This should be lettered 16A, 16B, and 16C; not 16, 16A, 16B. The other is on the key to the module — a circle indicates a trap door in the floor, not a trap door in the front.
Winners of the AD&D open tournament at Gen Con XIII in August, 1980 as announced in The Dragon #43.
The A Series:
The Temple from A1 "Slave Pits of the Undercity", original art by Jason B. Thompson
Sequels and Derivative Works:
The supermodule A1-4 "Scourge of the Slave Lords" (1986) was revised for character levels 7-11, to serve as a bridge between T1-4 "The Temple of Elemental Evil" and GDQ1-7 "Queen of the Spiders".
A sequel for 2e "Slavers" (2000) by Sean K. Reynolds and Chris Pramas takes place a decade after the events in A1-4 and is designed for character levels 4-5.
Hackmaster released "Smackdown the Slavers" (2002) by Brian Jelke, Steve Johansson, David S. Kenzer, Jamie LaFountain, Don Morgan, Mark Plemmons.
The 1e versions were re-released as "Against the Slave Lords"* (2013) together with A0 "Danger at Darkshelf Quarry" by Skip Williams, for character levels 1-3
*in conjunction with Dungeons & Dragons Collector's Series "The Scourge of Suderham" miniatures by Giorgio Bassani
(Left to right): Nerelas the Assassin, Mordramma the Priest, Feetla the Master Buccaneer, Ajaktsu the Magic-User and Brother Milerjoi the Monk
Also for 1e "The Last Slave Lord" in Dungeon #215 (June, 2013) serves as "A5".
Another 1e adventure "Lowdown in Highport" in Dungeon #221 (December, 2013) takes place in between A0 and A1.
Other Settings:
As a fan of the Mystara setting, I posted my thoughts on Setting modules A1-4/Slave Lords in the Gulf of Hule over at the Piazza, a while back.
Map of Hule from module X5 "The Temple of Death" with recommended location for the city of Highport from A1 "Slave Pits of the Undercity" (left) and the Gulf of Hule (right) from "Adapting classic AD&D modules to a Mystara campaign" in Threshold: the Mystara Magazine #22
Module X5 "The Temple of Death" described the land of Hule. The wilderness map included areas the DM was expected to detail further, including several unnamed towns. One of these, in southern Hule (see map) is an ideal candidate for Highport.
The population of Hule was described to be a mixture of humans and non-humans, mainly orcs, gnolls, bugbears, kobolds, and ogres. The rulers are chaotic and serve chaotic gods, and most of the human populace are either chaotic or neutral in alignment.
Placing Highport in the Gulf of Hule allows PCs adventuring in the Wild Lands to get embroiled with the Slave Lords, whose activities could be encroaching upon the civilized lands to the East, including Darokin, Karameikos, Ierendi, and Minrothad.
The proximity to Hule itself would serve well as a market for slaves from the Known World, given that slavery is likely a foundation of Hulean society. In fact, the Iron Ring in Karameikos could be allied with the Slave Lords.
Ayskudag works best in Mystara circa 1000 AC, since Highport in the Pomarj is directly north of the Drachensgrab Hills. There are even some choice nearby volcanoes for the City of Suderham.