" It's Party Time in Thyatis. . .
And simply everyone is going to the magnificent Villa Osteroplus, home of the wealthy old senator, Helenites. Raucous fun, exotic food, and even advanced betting on the upcoming Arena games are expected. Even adventurers just in from the outlands may meet the powerful here. So don your festive togas, for in Thyatis City there are important connections to be made and deeds to be done, duels to be fought and fame to be won"
One of the modules that in the past has been translocated to Clark Ashton Smith's Zothique has been Arena of Thyatis (DDA1) by John Nephew from 1990. Everything about this module has just the right amount of sleaze, forbidden weirdness, & old school nastiness to be perfect for a port over to far future decadent weirdness of Zothique.
Thyatis itself as blue print for a Zothique city state is perfect emulating a late Roman era style setting with a foreign ancient far edges of the ancient empire. Add in some of the suggestions from the D20 Zothique By George Hagar & your good to go with a low magic high action gladiatorial adventure romp. For added in Roman style weirdness add in the Castles & Crusades Codex Classicum by Brian Young (which needs an update Troll Lords).
Many of the classes from Codex Classicum can be adapted into the Arena of Thyatis (DDA1) by John Nephew for a Zothique feel. The weirdness comes from adding in a few monsters from the classic Fiend Folio but fortunately the heavy lifting has been done with the Classic Monsters & Treasures book for that otherworldly feel.
The party is captured by the Thyatis guards & sold into gladiatorial combat they escape during the module's events. And then begin adventuring on Zothique or they continue into the next module. For my money I'd go with escape during several pivotal adventure moments. Zothique has its own perils to deal with especially in the wastelands. And next we dive into some of the perils of this far future desert land. Once again its always Rodney Mathew's artwork that always echoes Clark Ashton Smith's Zothique for us.