Yearning For the Mines

I love games about mining. I played Motherload repeatedly when Flash was a thing, the alpha version of Minecraft when it was first released to the public, and uncounted runs of Terraria. There’s something deeply satisfying about digging a hole in the ground and pulling up treasures to fund better digging equipment to get deeper next time. When I played Astroneer with friends, I let someone else handle the vast majority of the base building and just mined out all the resources they needed – it’s an almost meditative activity for me. I’m more of a gatherer than a hunter.

Yet, despite how much tabletop roleplaying games love the idea of going underground to harvest treasure, dungeon delving doesn’t scratch that same itch for me: you’re moving through paths someone else made, not excavating them yourself. Tunneling through walls is typically either not covered explicitly by game mechanics or gated behind certain rare magic items, and even if you manage it, doing so tends to be regarded as a sort of cheating that sidesteps the intended experience of combat and puzzling.

All of that is perfectly fine, it’s still a fun style of game. However, I crave a tabletop implementation of what I love about computer-based mining games. I want to dig a hole on a sheet of paper. So, first of all, I’m going to present a streamlined subsystem for digging, which you may drop into your dungeoneering system of choice if you wish. Second, a set of items to help replicate that mining game feel. Finally, vertical maps and why you should use them.

Excavation

Although a relatively simple task at a basic level, digging is grueling work. However, it is also useful for mining ore, bypassing walls, making space to place foundations, burying one’s dead, setting up defensive trenches, sapping fortifications, and numerous other applications.

Performing excavation takes an exploration turn – in the strictest terms, let us say one hour, but how long a turn lasts varies by game and this ought not be overcomplicated. Excavation requires a shovel or equivalent implement, such as the scooped claws and polydactyl fulcrum thumbs nature furnishes for the mole. An action typically targets one cubic meter (one square on a standard grid) at a time, but how much you can accomplish with a turn depends on the material:

• Soft Soil: Sand, silt, or loam. May be removed with a single turn of work.
• Hard Soil: Packed, root-filled, or gravelly earth. One turn to loosen it up and a second to remove it.
• Stone: Rock, crystal, or concrete. Two turns breaking it with a pickaxe or similar tool, and a third turn shoveling out the resulting debris.

When you dig out a volume of material, it gets placed in a square of your choice adjacent to you. However, if you have a wheelbarrow or similar mode of conveyance, it can be hauled and dumped up to one room away as part of the action. You can also carry it one shovel at a time, which takes an exploration turn on its own. Placing soil and stone cubes can effectively let you alter the shape of the map.

A group of people can work together to dig out a number of cubic meters equal to their number, assuming there’s enough space for them to work – a narrow passage limits how many people can dig at the same time.

If you’re digging inside of a structure (such as a mineshaft, tunnel network, or mausoleum), you risk disrupting the stability of the passage. Whenever you dig, roll 1d6 – this is a type of overloaded encounter die.

1	Your noisy efforts draw attention. Roll for an encounter.
2	The ground trembles slightly. If rolled a second time, the room collapses.
3	You wear yourself out from toil. Take a short rest now or become exhausted.
4	A block adjacent to the one you were digging spills out along with it.
5	You find evidence of a nearby ore vein, monster tunnel, or other feature.
6	You find a fossil, uncut gem, chunk of ore, or similar minor treasure.

Geoengineering

Given how prolonged and exhausting of an endeavour excavation is by default, actually doing it doesn’t look especially appealing to the average party unless they have no other choice. Two ways exist to get around this: manpower, and machinery. The first option consists of simply throwing more bodies at the problem: hire a bunch of laborers to do the digging for you. This typically isn’t all that expensive on the budget of an even mid-level adventuring party, but does carry the disadvantages of wasted time acquiring the labor and possibility of workers getting dragged off into the dark by monsters.

Therefore, the second option: modern/futuristic technology, or magic items that function in an equivalent fashion. Below are some examples that support the premise of mining-based adventuring without obviating the process entirely. In addition, some existing items fit this milieu: boots of featherfall make it easy to descend vertical shafts, water breathing handles sumps, teleportation lets you return to the surface without a tedious ascent, and Stone Shape offers many opportunities for clever environmental manipulation.

• Explosives: Dynamite and the like. Explodes one combat turn after the fuse is lit. One unit of explosive breaks and removes any soil and stone in the cubic meter its placed on, throwing the material into adjacent areas. Each unit packed together increases the number of adjacent squares the resulting explosion affects. GM chooses adjacent squares when necessary.
• Power Shovel: Removes two blocks of soft soil or one block of hard soil in a single exploration turn.
• Hammer Drill: Breaks stone in one turn instead of two. Still requires a shovel to remove the resulting debris.
• Magma Mattock: Fully breaks and removes a cubic meter of stone, two meters of hard soil, or three meters of soft soil in a single exploration turn. Rarer than the power shovel or hammer drill.
• Sinkhole: Similar to a bag of holding, except that only minerals (inanimate soil, rock, crystal, glass, and metal) can pass through the opening. May be filled when excavating similar to using a wheelbarrow, except that the material is then weightlessly stored and can be called out specifically on command later. Can hold up to 256 cubic meters of mineral.

The Case For Vertical Maps

Despite the long tradition of verticality in dungeon design – especially in arranging stacked floors with greater risk and reward at lower levels – RPG maps typically still use a top-down style primarily concerned with horizontal space. This works well for tactical combat scenarios, but fails to capture the information most important to an excavation-focused game. Instead, one ought to use a vertical map: a slice of the z-axis showing what lies above and below.

If that sounds counterintuitive, think how widespread such a format is in the lately well-loved genre of Metroidvanias, in which the map is a central feature. They still provide ample horizontal space for encounters to take place in, but by restricting movement to one horizontal axis, they open up the (arguably more interesting) space of moving up and down as well. Not only does this provide easier mechanical representation of flying, swimming, and burrowing creatures (as well as falling distances), it also allows height advantages and terrain shape to matter beyond purely abstracted measures of “difficult terrain”. Moreover, it preserves and even emphasizes the element of marching order, while creating interesting design space concerning what rank a given person occupies – see Darkest Dungeon for ideas there.

The vertical map can work on two scales. First is the larger one, the wilderness hex map rotated to plot out the underground. I’d recommend using square instead of hexes, though, given the likelihood of structures roughly fitting those dimensions better when looked at from the side. The second scale zooms into a single one of these squares to view the geometry of a single dungeon, upon which the previously described excavation rules operate.

All of the concepts described in this post work well enough on their own, but I think they deserve a game tailor-made to them. In the near future I’ll put up a description of what I have in mind: the tentative name is “Deep Time”.

Featured Image: Plan of mines in Banská Štiavnica in Slovakia (1726) by Luigi Ferdinando Marsigli