@doppelgreener Something I thought of this morning: we've established (loosely) that leylines are affected by consciousness. Belief and emotion seem to attract and repel the lines. We've also established conclusively that leylines existed long before human history--heck, before oxygen was a significant atmospheric element.
If leylines aren't completely natural geographic features, this may imply something about anaerobic sapient life on Earth at shockingly early stages in its history.
A mineral-based life form like the bismuth dragon might be anaerobic, or have once been anaerobic...
If this implies a proto-history populated by mineral-based life forms, some of which survive to this day.... maybe think about dwarves having an ancestry in that direction, at least partially.
My version, until it's changed in play, is that some really ancient known human cultures --Egypt, Maya-- were concurrent with the latter days Atlanteans, but the Atlanteans were very reclusive and isolationist.
So people knew they existed, but details were sketchy even for their contemporaries.
I'm reading a Lovecraft short story right now where toad-beings on the Moon sent tiefling-like servants to trade with humans (wearing turbans and appropriate footwear) because they could pass as human while their masters couldn't.
Atlanteans may have done something similar, with only the less modified of them interacting with the outside world, and then only minimally. Maybe sort of like how Japan opened a single port city for trade with foreigners and kept a close eye on everyone who came ashore.
Those are the sort of isolationist concepts I'd toy with if details ever got pressed, anyway.
One of Plato's notions about Atlantis is that it had a central city and then a number of satellite outposts. Only the outposts were used for trading with outsiders.
(In Fate of Atlantis, these outposts were an opportunity to incrementally introduce Atlantean concepts, lore, and artefacts, saving up the city itself for the final part of the game.)