One of the greatest pieces of lore across the Talisman game is that ot The Lost City:

Did you write that? Its pretty cool. Yes, I like the prospect of exploring the Lost City. I'm not sure exactly how I feel about the placement of another board, but I'll want to see the continuing discussion.

No, i could! hehe, but this is in the lore of the Highland expansion rules… :)

In fact… mmm, i´ld say that the Ancient Wizard, who made the Crown of Comand, maybe was one of the forgotten race said in this lore…
 

Well, I've always felt that many of the spaces between the various boards have their own story, or certainly could be parts of a bigger story.

As I look at the title of your post, I realise that you could also mean a new game that is based on The Lost City, not just a separate board or situation for an expansion. That is pretty cool.

In general, Talisman reminds me of The Witch World books by Andre Norton. There are Rune gates that take people in and out of the Witch World, totally, but also just to other parts of the world. But the Lost City, with its hints of older, elder races reminds me of the Lore of the Witch World too.

Perhaps a Lost City themed expansion would highlight advanced Mage types who in Witch World terms present as semi-Sci-fi oriented (ala Timescape, perhaps), but remnants of the advanced, but fantasy based world (Magic as Super Science?)