More specifically, why hexcrawl in the Veins of the Earth?
Given the entry costs and ludicrous risks, why would any sensible party of adventurers bother going into the Veins? Leaving aside accidents, idiocy, and lies, what could possibly convince a surface creature - someone who likes three square meals a day and feather beds - to crawl down satan's gastrointestinal tract or live in Patrick Stuart's nightmares?
1. LootVeins loot makes conventional dungeons look like a discount clothing warehouse after a fire sale, in a hyper-inflationary economy, right before the coldest winter on record. Your gold crowns and polished gems and magic wands are bent clothes hangers and ragged Snoopy t-shirts compared to the stuff in the Veins.
It will get to the point where gold is too heavy and too pointless to transport. Pouches of strange metals will adorn your back. You'll carry a sword that can cut a syllable in half but your face will be streaked with clay and muck. You'll cut your hair off and file your teeth into points, but you'll also find a machine that spins music into cloth. When - or if - you emerge, changed and warped, you will change the surface world forever. There are treasures in the Veins that are the seeds of empires.
You'll probably need to find a way back to the surface once you've finished looting an area. Most factions have a route or two; they won't share them eagerly.
2. ControlCarve out an empire of your own. Wear a fancy hat. Sit on a throne and judge people. Earn eternal fame. The charitable view is that surface-dwellers, blessed with an education, a life of comparative leisure and safety, and a worldview based on control, make ideal leaders and warlords in the Veins.
The uncharitable view is that surface-dwellers are too stupid to know better.
Start small: a single village, a cleared dungeon, or an empty cave. Recruit followers with promises of food and safety. Set your enemies against each other. Use horrifying weapons or enslaved creatures.
How to feed your empire:
|Spawning fungid cluster (1 Myconid/day)||5/day||Coal|
|20 Sonic Pigs||5/day||Cave slime, 1 swineherd.|
|30 Cave Centipedes||5/day||Cave slime, 1 centiherd.|
|Cave cricket swarm||5/day||Cave slime, 2 cricket-keepers.|
|1 Troll, chained.||5/day||2 Troll-choppers.||Troll may escape, mutate, split. Troll meat is infectious.|
|Lamenter Nest||5/day||1 Lamenter-raider.||1-in-6 chance Lamenter-raider goes mad each day.|
|Souls||1/month/soul.||Need an extractor or a supplier.||Inherit personalities, become possessed. Very evil.|
|Divine Intervention||1 faithful person||Absolute unwavering faith.||Only supports 1 holy figure (or possibly a small tribe).|
|Raids into Painted Worlds||100/month/painting||Artists, powerful magic, 10 raiders.||Can become trapped in painting, let other creatures out.|
The more people you can support, the more territory you can control.
If you support 5 people, you have a village.
If you support 20 people, you have a fortress.
If you support 50 people, you control most of a hex.
If you support 100 people, you completely control a hex (or mostly control 2 hexes).
The size of your holding is purely dependent on food. Money is useful, trade goods are nice, but if you can't feed your followers they will feast on your flesh and tear down your cities and your works. Civilization is three missed meals away from anarchy, but everyone in the Veins has already missed the first two meals.
In the Veins, 100 people is an enormous army, possibly too difficult to move. Defenses are easy and attacking is difficult so no one fights fair. If you plan on fighting a faction, make sure you're prepared to be stabbed in the back. Or the front. Or from above.
Don't fight fair.
3. QuestsThere are capital-g-Goals in the hexcrawl. They are completely optional, but some players like having a mission. Spoilers.
1. Kill the Great White Fungus
It's a whale-sized mushroom that steals peoples legs and runs around on them, kicking and having a grand old time. Anyone bitten by it goes crazy and wants to kill it, but for some reason tries to recruit people with lovely shapely legs to help.
2. Kill the Castillian Caddis Fly Larvae
It will hatch into a Castillian Caddis Dragon. It wants to create lots of magic weapons to ensure its eggs find fertile spots to hatch and grow. To this end, it will cause apocalypses. Heroes (with shiny magic swords) will arise, fight, die, and lose their swords. The world above (and everything nearby in the Veins) will enter a catastrophic and violent phase lasting centuries.
3. Kill a Dragon
There are 5 dragons and you can fight all of them.
4. Find a McGuffin in the Ruins
That's what the ruins are for. Put your vital quest items there. Resurrection machines. A direct line to the Gods.
5. Topple a Villainous Faction
The Illithids, the Ghouls, or the Drow seem like good choices if you want to smash an evil system and replace it with utter chaos. Rescue the captured princess(es) from the dragon Kaseldrake. You know, standard heroic stuff.
6. Assist a Faction's Quest
|Antling||Find a path to Hell.|
|Dvergr||Find Homunculite, weaken other factions.|
|Ghoul||Rebuild Illiam, stable source of meat.|
|Illithid||Brains. Lots and lots of brains.|
|Olm||Food. Lots and lots of food.|
ChallengesOn the surface, everything follows the same rules. Bugs, bears, and bugbears all need to eat. In the Veins:
-The Drow eat beauty.
-The Olm eat flesh but sleep for centuries.
-The Dvergr need alcohol like a plant needs sunlight.
-The Antlings get their food from the surface.
-The Myconids eat coal.
On the surface, there is an overarching framework of society. The feudal state holds the world together. There are outsiders and invaders and disruptions, but you are either inside the system or outside it; there's no third way. But in the Veins, there is no cohesion, no single system. Every faction has its own worldview. Common ground resembles no man's land - contested, cratered, and occasionally hit by political artillery.
Planning ChaosI've designed the Veinscrawl to contain a lot of potential energy but minimal initial kinetic energy. The situation, on paper, is fairly stable. The PCs are the ones who will tip it into lovely and profitable chaos. Their actions and interactions with the factions and hexes will start to spiral out of control.
If any of the hex entries seem boring, just remember to append, "And then the PCs arrived."