So, inspired after reading Dungeon of Signs' Underdark posts, and a few other things, I wanted to run a game where a single religion has pretty much conquered or converted the entire continent - some kind of Light, Fire and Brimstone bullshit.

The PCs come from across the continent, and are the undesirables - non-human races, uncivilised tribes, criminals, thieves, political dissidents, sorcerers, whores, the diseased and mad, and hold-outs from conquered religions.

Most are used as slave labour, but the PCs are part of a special operation - bringing the Light to the Underworld, a place of monstrous beasts and weird races.

They will be given a small amount of supplies, with semi-regular drops while they build the first settlement in the Underdark.

What I'd like some help with is the system - what can be used to handle the hard-scrabble survival, with resource tracking, deadly combat, weird magic and some large-scale settlement building rules?

Tackling the 800lb gorilla right off the bat — why not some edition of D&D?

Torchbearer would work really well for this, if I correctly understand what you're looking for. You'd have to figure out appropriate skills and obstacles for settlement building, and tie successes to which "town phase" facilities were made accessible, but other than that it perfectly captures the feeling of hardscrabble adventuring in the claustrophobic darkness. Maybe take a look at that.

Is that something ACKs could handle? I'm not all up on the system but folks talk up how well it does with domain building and such. Seems like that could all be moved underground... mushroom economy.
The idea reminds me of an awful book I read, The Descent (no relation to the movie), that had a modern day military operation attempting to establish a foothold in a vast underworld filled with hostile creatures... sending out expeditions.

Quote from: The Butcher;849197Tackling the 800lb gorilla right off the bat — why not some edition of D&D?

That was my basic assumption, but its always good to stretch your mind, you know?

I'd probably run it with a retro clone like LL with some stuff from the AEC, or maybe with LotFP.

Important thing would be to track consumables religiously, along with encumbrance. If players aren't on-board, this can be difficult, since you can't offload work onto them.

That said, someone here posted a long while back how they managed. iirc, it was pretty clever--basically you use a piece of graph paper as a "turn track" on which you cross off units of time (you might have separate minute/hour/day tracks). Then put a symbol N boxes after present to indicate the time when something will be used up. That way you don't have to track each thing separately, you just watch the passage of time.