Tracking light during a dungeoncrawl is important, at least in the old school or OSR method of play, because it, along with other mechanics such as wandering monster checks, adds a time pressure to the adventure. It also plays to the tension created by the oppressive nature of darkness and the unknown. As long as have our flames held before us, we keep void at bay. To achieve these effects, tracking light becomes a paramount concern and, well, it's a bore. I hope this system will make it at least slightly less so.
Candlepower -- the power of candles at your command!
The term candlepower was coined in the mid-nineteenth century. As Wikipedia tells it:
The term candlepower was originally defined in the United Kingdom, by the Metropolitan Gas Act 1860, as the light produced by a pure... candle that weighs 1⁄6 pound (76 grams) and burns at a rate of 120 grains per hour (7.8 grams per hour).
Now that you have that background, forget it, don't worry about it. I bring it up only to avoid (a fool's errand, I am sure), folks bringing it up later, as in "but that's not what candlepower means!" I don't care because, right here, I am redefining it, for our gaming needs, as simply one Dungeon Turn's worth of light.
One Candlepower is equal to one Dungeon Turn's worth of light.
We can now convert light source durations from minutes to candlepower:
one torch = six candlepower
one lantern = twenty-four candlepower
You might be asking yourself, and rightfully so, what use this serves and I am oh so glad that you did. Candlepower becomes a meta-currency for the party to spend in order to explore dark places.
I sense the glazing over of eyes so let's run through a bit of an example:
You are the Referee and your party is in the dungeon. Every Player-Character has marked their carried torches to candlepower units. The Fighter carries 24 candlepower (from 4 torches), the Cleric and Wizard have 8 candlepower each (from 2 torches a piece). The Thief, skulking as is their wont, has 24 candlepower in the form of a flask of oil but only if there is a lantern, which there isn't, so, effectively, they have zero at present.
As the party explores, you, as the Referee, call off the passing of each Dungeon Turn. As each new Turn begins, one of the party must spend from their candlepower reserves to keep the light going.
On Turn One, the Fighter spends one of their candlepower (bringing them down from 24 to 23). On Turn Two, the Cleric spends one (bringing their supply down to 7 from 8). On Turn Three, the Fighter spends another of theirs (dropping from 23 to 233). And so forth.
How are we LIGHTENING (ha HA!) our burden here?
By converting our light sources to candlepower, though making note of their types (torches vs oil) if and as needed, we are effectively abstracting light but without removing it as a resource or diminishing its import. What we are eliding is the counting of physical sticks or flasks that are passed around and consumed. As long as there is effective candlepower to spend, we assume whoever is tasked with holding the light is holding something with enough fuel left in it to make light.
If we need to spend one of those sticks or flasks by throwing a torch down a well or converting that flask of oil into a Molotov cocktail, we simply subtract that number of candlepower from the party resources.
If we incorporate this into our dungeoncrawl procedures, it slots in easily into the structure of the Dungeon Turn. On a new Turn, one player must spend a candlepower to keep the light going. The party could even pool their supply physically in the form of coins, chits, or chips, or the VTT equivalent, and collectively spend them as they go.
Going even LIGHTER!
For an even simpler abstracted version, we could abolish the distinction between fuel types (torches or oil) altogether and simply track candlepower. If a lantern of some type is present, it is assumed that the fuel is compatible or, if not present, that it manifests as a torch.
Using candlepower with overloaded dungeon dice
If you've never heard about overloaded dungeon dice, it's a mechanic for leveraging a wandering monster style check for more than just monsters. There are many different variants of this mechanic but I first saw it on the Necropraxis blog and that is the version I will reference here.
When the party moves into a new area or spends time on an exploration activity, roll the encounter die and interpret the results as follows.
Encounter
Percept (clue, spoor)
Locality (context-dependent timer)
Exhaustion (rest or take penalties)
Lantern
Torch
You'll notice that 5 and 6 indicate light events, one for lanterns and one for torches. In the original blog entry, a note is made about how to handle these results but we can simplify this and apply our candlepower mechanic thusly:
Encounter
Percept (clue, spoor)
Locality (context-dependent timer)
Exhaustion (rest or take penalties)
2 candlepower
4 candlepower
What does this change?
In the original version, the recommendation is that torch will just go out on a roll of six and a lantern will exhaust in three or four results of five. Moving the candlepower, we don't need to invoke another variable to track (lantern "strikes") and we get to mitigate what can be a harsh bit of randomness with torches potentially extinguishing in rapid order.