Persistent area..

Was trying to think of a way to incorporate all backgrounds into one massive
ongoing content idea. This goes along the lines of a tower to the gods or
pit to the depths of hell.

To begin with, Evil or Good religious will determine the site of the proposed
construction. Either the Tarms have insight into their deity and find a point
where a large enough structure could breach the barrier between realms.

Once the site has been determined, Civ folk would have to build that level
with whatever materials have been determined by the religious types as
appropriate. After that, a certain amount of magic is imbued into that level
of the structure to reinforce it and channel the energies to open the gates
to other worlds.

Once 5,10 or however many levels have been developed, a gate to another
dimension opens on that level and nasties flood the tower to be cleared
by appropriately burly types.

Rinse and repeat. but content that would have to meet some trigger to carry
over to the next boot. Finish construction to be able to go to next step,
clear this level of all monsters to be able to build next level. you get
the idea.

As a means of trolling, the gods have built a failsafe device in that any
mortal can strike the base of the tower for 30 days in a row and cause it
to all crumble down. The gods might even offer a reward depending on the
size of the structure for the brave mortal to remove this example of human
arrogance.

This all has a lot of things in common with the tower of Babel.. a bunch
of mortals getting together and building something so vast.. as to challenge
the gods themselves. Or alternatively, you could be digging into the bowels
of hell.. along the lines of those dwarves in LoTR. At any rate.. content
that is unlocked when players reach milestones.