Yes, GURPS and the Traveller setting were a good fit.
I do have a minor aesthetic regret that SJG put the original "Beowolf calling for help" on the cover rather than the ad text of a ship replying "Hang in there Beowolf. Help is on the way."
I'd model it on the Grand Bazaar of Istanbul. So a covered market in a big city - the largest city in the region if not the world. Shops, lots of shops, with any 'adventure' arising from mercantile interests and/or the criminal underworld.
It's easy to find the shops the Grand Bazaar has today, but for a typical medievaloid or at least pre-industrial-revolution fantasy setting, I'd try for a deep dive into the history of what was being sold there 300-500 years ago.
Istanbul/Constantinople/Byzantium/and at least 2 other names is truely one of the great cities of the world. It's like a real life Waterdeep, complete with an undermountain.
Istanbul, for which many wars have been fought throughout history, literally keeps another city alive. Almost every street has galleries, tunnels and dungeons stretching hundreds of meters below the ground. Some of these are structures that were built on them because they got old over time...
kasifiz.com
more concepts:
The Adventurers’ Outlet
Outlet mall for slightly defective magic items. “Wand of Fireballs – one fireball left, maybe.”
Customer Service Desk
Staffed by a minor god of Bureaucracy. Returns require three forms and a sacrifice of patience.
Lost & Found A maze-like repository of every lost object ever misplaced in the multiverse. Adventuring hook central.
Security Office The mall cops are paladins who take their Oaths very seriously. Possibly too seriously. Oath of the Mallcop!
now some plot hooks
The Black Friday Siege: The gates open to another realm of shoppers. The paladins of Customer Service are overwhelmed.
Mallrats of the Multiverse: A group of teens accidentally unleash an ancient sale-golem from the Discount Catacombs.
The Escalator of Ascension: It only goes up. Always. No one knows where.
The Great Return: Someone tries to return a cursed item that’s rewriting reality, but the receipt has faded from time itself.
Expansion Project: The mall begins to consume nearby villages. Is it an economic miracle or a spatial infection?
