Updated: Oct 19, 2022
While Dungeons & Dragons is mostly a game about going into adventures that take place in fantastic locations, which the players seldom revisit, Sometimes players get attached to an NPC or a particular place. This is especially true if this object or person is profitable for them in one way or another.
It is somewhat common for players to want to own things, including castles, strongholds and establishments. But some players like to go the extra mile and really acquire something unique, like a mine.
This has actually happened to me and to at least another DM I know. So here I will share my experience and tips on running a mine for a party of PCs.
I will begin by pointing you into a couple of supplements for running either mines or general geological stuff. Then I will advise on some mechanics that I have used to simplify "venues" for my players in other campaigns.
To begin with, I would recommend two supplements for enhancing your mine. The first one is called MINING GUIDE, written by Angry Golem Games. I leave the link to their Drivethru RPG page. It's at 4.8 dollars, so it's not really expensive.
Mining Guide: https://www.drivethrurpg.com/product/294792/MINING-GUIDE
Now for a full disclosure. I do not completely like this supplement, I find it somewhat lackluster and quite complicated. That being said. I used some parts of it to great effect with a mine my players had found and cleared. It has a lot of small things you can implement in your game. My personal recommendations would be the By-products, lifetime of the veins and smelting sections.
The second supplement is called "The Mineralogy Manual". It is/was a kickstarter product.This one focuses more than anything in specific minerals, stones, metals and the like. It is super detailed on the things you can get out of the mine (it has more than 200 products), as well as their special properties (magic or mundane) and value. My favorite sections of this book are the Crystals, gems and elements.
A problem with this one is the quality of the book. It's lackluster and quite boring.The other problem is the price... It's at 52$ (the pdf) at the moment, and is currently on sale. To me that is overpriced for a pdf, I would believe that around $20 would be more fair, so it's up to you. I had the fortune of backing it when it launched in Kickstarter and got a good deal. I'll leave the link to their store page should you want to buy it and support them.
Mineralogy Manual. https://www.drivethrurpg.com/product/359125/The-Mineralogy-Manual
Take the mine, read the Mining Guide pdf and steal a couple of sections from it. This will grant your mine verisimilitude, and will make it much more solid.
Take the Mineralogy manual, choose at random some "products" and roll on some tables to see how much extra things one can find in the mine. Usually -in real life- mines do not only give exactly one product, you can usually transform a mineral into several products that satisfy different needs with them.
Make a map of the mine. I recommend using Random Dungeon Generator Lite to design it, it's fast and easy
Divide the mine in sections. Assign a lifetime to each section, and a product and by-product to each one.
Figure out approx. how much material value is expected from it. This is invaluable so you won't over(or under)estimate the amount of money it will give to your players. Otherwise it might be too much of a hassle to maintain it, or it could completely break the game by making your players ridiculously rich.
Figure out how much time it will take to exhaust the mine. This will depend on how the players upgrade it, how many workers they hire and many other factors. This is important if you (like me) like to keep things consistent and like the resource management and empire building aspect of the game.
Now that you have a real mine. Let's make some drama around it to make it more interesting.
Make a Master Table for the mine. Ideally it contains two tables, one for lucky events and one for unlucky events. Have the players roll a "luck check"(d100) every tenday(or whenever you want), and assign a value for each category. Below you will find a sample table. Note that this should be tailored to suit your campaign or players.
Bad Luck events (1-50)
Good Events (51-100)
While searching for new veins, miners accidentally uncovered an entrance to the underdark, now monsters are swarming out of it.
Miners found the foundations of a ruined temple for an ancient deity. Some artifacts may be recovered, restored and sold for profit.
Lady Zarzehel (the party’s lead antagonist) has sent a contingent of her undead minions to disrupt the mining operation.
The creation of jobs in the mine for local dwarfs hasn’t gone unnoticed by the Church of Moradin, they now offer free healing services to the party while the mine is in operation.
A small earthquake has collapsed an entire wing of the mine, several workers have become trapped and will suffocate within 24 hours
A new ore vein has been uncovered. It contains Nustum, an expensive chain metal that can be used to craft magic weapons.
The miners discovered a sarcophagus buried in the silver ore wing, they opened it and triggered a curse, now they are turning into mummies.
Sir Gwelmint of Elturgard (the patron of the PCs) has offered them to run the mine and build around it a sprawling town with a stronghold for the PCs for a 50% cut on their profits.
The PCs receive a letter from the Zentharim. It demands they hand over control of the mine immediately, or else.
After a small earthquake, an entire new wing was discovered. It contains 1d4 new metals and 1d4 new elements to mine.
The miners opened a new tunnel, it led directly to the lair of an adult blue dragon. The dragon has claimed ownership of the mine and is demanding the PCs return everything they took out of the mine.
A tomb was found while mining the Granius ore. It contains a small dungeon for the players to explore and a legendary magic item rests inside.
9. This table works the following way: First you or your characters roll a 1d100. That’s how you determine if the event is a bad luck event or a good one. Then you roll -in this case- a 1d6 to determine how good or bad the event is. Remember that the best way to do this is to craft your own table to reflect the things your players like and would be excited to deal with.
10. The table can also contain “neutral” events, which may present both a benefit and a downside.
11. The idea is to transform the mine into a source of drama, problems and rewards so players feel good about having acquired it.
12. Craft a letter for their Next session. The letter is from the foreman, it includes the developments of the mine for the past tenday, month or whatever time unit you want to use.
13. Make the events inside the table connected to the PCs, the story and perhaps even the villain. In the sample table, half of the events are connected directly to other actors in the campaign, which transforms the mine from a boring “it gives you x gold per tenday” to an actual pivotal location that gets the players invested in your game.
And that's it.
I know it might sound intimidating, but it's not really. It took me like 2 hours to design a mine from the ground up. The biggest time sink is actually reading the supplements, stealing what you like and figuring out how to implement it. Once that is done, the mine will come up almost on its own and won't need constant care. It's a really solid system.