Character encumbrance has long been a hot-button issue in tabletop game design circles. Part of this is because in our time-starved modern lives, players have a bias against bookkeeping of any kind.
Another part, I suspect, is mis-calibration of stakes (the short version: tracking encumbrance necessitates genuine character choices and can result in more interactions with the game world, e.g., through hiring and managing porters and mule drivers, rewarding players for considering ship passage for long journeys, and so forth. But it doesn't do much more than that).
Once you're past the 'should we even bother to track encumbrance?' stage - and to be clear, I think tracking encumbrance benefits all but the most rules-light of roleplaying games - you come to the 'how do we track encumbrance?' stage. And there are, as far as I can tell, two main approaches here.
The first, default, approach is to use weight, summing the weight of each item carried and comparing the total to rules for maximum weight or weight penalties. It's simple, but it's a lot of (also simple) maths, which can be a deal-breaker for some even in the age of omnipresent computing. It also doesn't model bulk, and requires the GM to constantly adjudicate the exact weights of new items.
The second approach is to use abstract item slots, often as a proxy for both weight and bulk. You can carry N significant items, where 'significant' is loosely defined, and N is fixed or character-dependent. Most frameworks further prescribe that particularly heavy items take multiple slots, light ones stack into a slot, and so on. This is both easy and plausible, and requires less GM adjudication.
I think the second approach is better, but that there's something fundamentally missing.
An aside about bulk
Consider a really long wooden plank, say a three-metre-long 'two by four'.
- A bundle of five such planks would weigh about 15 kg, and you would struggle to perform basic movements while carrying them. Forget being able to quickly turn or catch a ball, let alone vault a fence or climb a wall.
- Compare a mail hauberk and coif, which also weighs about 15 kg. With the right belt and straps to support its weight, you barely feel that weight. It makes almost no difference to movement.
- Per the the US Army Field Manual (1990), the recommended load for an American soldier (who we might consider as our 'fit and healthy character' default) is 31 kg (69 lbs), including what they're wearing. In practise, this rises to more than 50 kg (110 lbs) in the field. So it should be trivial to wear 15 kg of mail armour; at the same time, it should be extremely awkward to carry 15 kg of long planks, and make many tasks essentially impossible.
- Lots of tabletop games can involve carrying awkwardly shaped items from time to time: polearms, long guns, ladders, wizard staves, downed comrades, big coils of rope, small creatures, the occasional piece of looted furniture.
So bulk has to be a factor. Why doesn't the abstract-item-slot work, then?
Encumbrance means two things
When we're talking about character encumbrance, we mean two different things.
- Over long treks, encumbrance is how much weight and bulk your character can carry without becoming fatigued.
- In short bursts of skilled exertion (like fights, climbing, avoiding traps, and so on), encumbrance is how much weight and bulk your character can carry without being impeded.
- (There's also the separate question of how much you can lift and carry over short distances/periods if you really have to, but games usually do include specific rules for this)
Long/strength/fatigue encumbrance and short/quick/impede encumbrance are very, very different.
Over long distances (say a day of walking), a moderately robust character can carry 15 kg in a backpack and another 5 kg of clothing and miscellanea, no problem. The exact same character, in a fight or keeping their footing on a ship in a storm or otherwise needing snappy movements, ought to be severely disadvantaged compared to one not wearing the backpack. And disadvantaged compared to a character wearing that 15 kg as armour.
Ask a HEMA practitioner about fighting while carrying something big enough to change your centre of balance (especially if it raises it or moves it laterally away; a backpack does both). It's a nightmare to deal with!
When it comes to both long/strength/fatigue and short/quick/impede encumbrance, the difference between your typical fantasy character and a medieval knight on campaign is that the knight has a coterie of dedicated servants to haul things around for him: pages, squires, swains, manservants, sarjents, standard-bearers, chamber servants, etc. Not to mention having a warhorse, a riding horse, and a packhorse, as well as possibly some pack mules or donkeys. The fantasy character has the same amount of stuff and, in most games, carries it personally and fights with it on their back.
So a game needs two subsystems: one to deal with how much you can carry over long distances before tiring (long/strength/fatigue encumbrance), and one to deal with the impact of equipment load on tasks that requires speed, agility, balance, and deftness (short/quick/impede encumbrance).
Do you really need both subsystems?
Most games will let you have a backpack (or the fictional fantasy medieval equivalent of a modern backpack) that you can remove and drop when you need to move quickly. A common house rule in practice is to go as far as to assume that you always drop your heavy load in appropriate circumstances with no words exchanged(!), and because of that, you're never penalised by it(!)
But there can be situations where that's not possible, because you're flying or carrying an unconscious comrade or suddenly ambushed or whatever. Those situations aren't even that uncommon. So there's a need for rules to cover them.
Also, in general, shrugging off a load takes time, even if you have a fictional fantasy medieval equivalent of a modern backpack, and that's time you could otherwise spend acting.
Also also, dropping your gear creates a new target (unattended equipment).
Also also also, there are some common tasks which I suspect are being done 'fully loaded' even though they really should be affected by short/quick/impede encumbrance: sneaking, searching for traps, defending against surprise attacks, fleeing, posturing against a possible aggressor, etc.
What I'd like to see, part one: Bulk vs weight
Awkwardly sized and shaped objects need something to set them apart from heavy objects, even if it's just a multiplier to their perceived weight (2x effective weight for awkward objects, 3x for really awkward objects?). This certainly applies to quick, deft movements, but arguably also to carrying things long distances, so the multiplier could be a general one: bulky and awkward items just 'count as' a greater number of items.
15 kg of worn mail is trivial in almost every circumstance. 15 kg of long planks (or bundled spears, or sacks of coins) is all of your attention and all of your arm strength, all of the time, and a sacrifice of your ability to do anything by reflex other than 'dropping these heavy objects'.
What I'd like to see, part two: A separate subsystem
Encumbrance systems in the current zeitgeist, such as abstract items slots, work really well for the question of endurance, i.e., for long/strength/fatigue encumbrance. But those systems range from 'far too generous' to 'entirely inadequate' when it comes to impeding movements during short bursts of skilled exertion, i.e., short/quick/impede encumbrance.
Carrying more than you can physically bear should make you exhausted and sore over hours of travel, i.e., convey a physical malus. And carrying enough to impede you should make you clumsy and slow at those moments when you need to be deft and fast, i.e., convey a malus to many task outcomes (such as a penalty to certain dice rolls).
From the point of view of verisimilitude, a character ought to be stacking more and more penalties the more weight and bulk they have on them. In the interests of smooth gameplay, though, you're probably looking at having a few 'bands' of acceptability or detriment, where the 'default' in a fantasy setting would comprise armour, a couple of weapons, and a bandolier or belt pouches; you would then adjust based on deviations from that norm:
- You should get a hefty bonus on most physical tasks if stripped down to basic clothing (so a rogue takes just their clothing and a small pouch of tools to climb roofs and break into houses; a fighter best shows off their prowess when fencing with sword, buckler, and jerkin, but it's not in practise it's not worth the risk of going completely unarmoured).
- You should get substantial penalties if you're carrying even a portion of your full 'travel load' (bedroll, a week's food, toolbox, belt lantern, backup weapon, bow, spellbooks, and so on).
And crucially, the maximum load a character can comfortably carry long distances must be far higher than the maximum load which they can carry while moving in quick bursts without penalty.
Consequences
I haven't tried playing like this, but I'd like to.
The consequences I predict are a greater sense of verisimilitude, an amount of grumbling from players commensurate with their not getting any in-world benefit out of it, greater attention to base camps and supply caches, less 'we buy one of everything' at the first treasure windfall, much more hiring of hirelings, and a rise in value of extradimensional spaces, levitation, all-terrain vehicles, and other utility gear.
Addendum 27/05/2023: The above of course applies to traditional roleplaying frameworks. I think that in games which veer away from "roleplaying game" and into "collaborative storytelling", rules like "you are carrying whatever is dramatically appropriate, if reasonable" (or more structured variants of that) are perfectly good solutions.