Every campaign has some kind of logic, tone, or theme to it, even if unwitting to its designer. The longer you play the more this dynamic entrenches itself, creating through happy accident some kind of larger coherence behind it all. The various disparate mysteries start to have underlying and connected causes and overtime it's impossible for both players and GM not to build a sense of meaning behind it.
Both the Austin and San Antonio attempts at this campaign were very much a return to the sharply-bounded sandbox that was the height of fashion in old school circles 2-3 years ago. In that first year there really was no overarching plot, no real machinations by NPCs, nothing but pure wilderness and dungeon exploration and what the players brought to it through their own projection and co-creation.
But month after month that interplay built that famous onion-layering of mystery. I have joked (perhaps only halfway come to think of it) about the “cosmic” secrets of the HC before.
At any rate, here is one of the “outer mysteries”, the setting logic that makes for the day in day out arena that players walk around the HC in. That is in a player-driven world it produces the signposts of where exploration (adventure) are most likely to produce something fruitful. It's a campaign logic that hangs on a more literal, deeper-running meaning of the old D&D designation of geographic zones of civilization, borderlands, and wilderness areas.
The Corelands are human civilization. Though wars, political machinations, plagues, and the rest of the human drama play out here, from the perspective of Cantoners these lands are something of a movie facade. There is no whiff of the “Weird” here, magic doesn't function. Monsters and adventure has no real place here. Like a fantasy Oakland there is no there there.
Whole areas exist in the hills were the Veil Between the Worlds has ripped asunder filling the areas with the flotsam and jetsom of many worlds and times. This is the Weird. Here be monsters and golden, onion-domed barges and great cyclopean halls filling mountain-tops. Geography is exaggerated and uncoupled from the expectations of other lands.
The rising tide of such cosmic strangeness produces a startling density of these so-called sites of adventure. It's not uncommon to walk a few hours from one only to uncover another and then another a short jaunt away.
The Borderlands is the contested zone between. Magic functions here, yet civilization exists here too even if sparsely and tentatively. The entirety of human settlement in the Hill Cantons (the political/regional entity not the campaign) is found here and it is rippled like a marble cake with pockets of the Weird. As such adventure can be found here, but it involves neither the big-ticket risks nor the rewards of exploring the otherworldly regions.
Life here for humanity is tainted by the contact with the Weird, indeed literally many who return back to the core from here die quietly and strangely of maladies in the night. Though a rough frontier, fashion is extravagant and quick to change. Doctrines of the mind are extravagant and quick to heated dispute in their over-elaboration.
While desperate, life here also carries with it the freedom from the dull routine. Heretics, runaway servants, poets, and the sociopaths and picaros calling themselves adventurers flock here as a result.