Most RPGs require players to carefully track the items they carry. For instance, in 5e, you track how many pounds each item weighs, and the total weight you can carry is 15 pounds times your Strength score: for example, with a Strength of 10 you can carry 150 pounds (!). While 5e doesn’t require you to specify where your items are (e.g., your hands, your pack, your belt, etc.), anti-hammerspace systems require you to specify such details. Such detailed inventory and gear systems are simulationist.

As a result of such rules, before setting out on an adventure, players with a lot of possessions agonize over what to bring and what to leave behind. And what they may want to buy before going on their trip.

In contrast, Apocalypse World popularized the idea of quantum gear, which can be decided later:

Things pretty, portable, and convenient to trade are called ‘oddments’ or ‘jingle.’ In character creation, the players can describe what their characters’ oddments are, or just list ‘oddments worth n-barter’ and leave them to be described later on, if ever.

Closely tied to quantum gear (the name comes from the idea of quantum superposition) are abstracted items. Apocalypse World has its angel kit—

An angel kit has all kinds of crap in it: scissors, rags, tape, needles, clamps, gloves, chill coils, wipes, alcohol, injectable tourniquets & bloodslower, instant blood packets (coffee reddener), tubes of meatmesh, bonepins & site injectors, biostabs, chemostabs, narcostabs (chillstabs) in quantity, and a roll of heart jumpshock patches for when it comes to that. It’s big enough to fill the trunk of a car. When you use it, spend its stock; you can spend 0–3 of its stock per use. You can resupply it for 1-barter per 2-stock, if your circumstances let you barter for medical supplies.

Dungeon World, one of the first hacks of Apocalypse World, smashed these two ideas together:

Adventuring Gear 5 uses, 20 coins, 1 weight
Adventuring gear is a collection of useful mundane items such as chalk, poles, spikes, ropes, etc. When you rummage through your adventuring gear for some useful mundane item, you find what you need and mark off a use.

So you could turn Adventuring Gear into items, which you would then add to your inventory. As Tam H. has described it, “So ‘I need a torch, okay, I’ll mark off a use of my adventuring gear, now I have a torch and four uses left.’ What’s in the box is undetermined until you need it. It’s a way to streamline bookkeeping.”

Dungeon World also has a Bag of Books, but it functions more like a usage tracker or consumable item:

Bag of Books 5 uses, 10 coins, 2 weight
When your bag of books contains just the right book for the subject you’re spouting lore on, consult the book, mark off a use, and take +1 to your roll.

Jeremy Strandberg rewrote this to be as quantum as Adventuring Gear:

Books fragile, slow, 3 weight, 5 uses
When you expend a use, name one of your books and tell us what it describes. The GM or any player can veto a topic they find too silly, too broad, etc. Henceforth, when you take the time to reference the book, take +1 to Spout Lore about an appropriate topic.

This was perhaps inspired by a more general move from Jeremy’s Stonetop:

Have What You Need
When you decide that you had something all along, transfer a mark (or marks) from your “undefined” inventory to a specific item or a slot. If you mark a slot, fill it with a common mundane item or something from your personal possessions.

Alternately, you can expend a use of supplies to mark an additional small item/slot ( ).

Whatever you produce, it must be something you could have had all along. The GM or any player can veto unreasonable items.

(Jeremy has blogged about the development of Stonetop’s inventory system.)

Uses, load limits, and encumbrance are ways to prevent the quantum gear accessed through this move from being overpowered.

In my table comparing Dungeon World to five of its hacks, I have an overly succinct summary of how much these games embraced abstract and quantum gear:

  • “Primarily concrete items” – my summary of Freebooters on the Frontier 1e’s fairly traditional inventory system.
  • “Some quantum items” – Dungeon World has Adventuring Gear and then has abstract consumables like ammo, books, rations, etc. For instance, you mark up to 3 uses of ammo and then lose it, as opposed to tracking 20 arrows or quarrels.
  • “Many quantum items” – How I described Chasing Adventure, Homebrew World, and Unlimited Dungeons. For instance, Unlimited Dungeons has a “more abstract and tag-based approach towards wealth and equipment” and has Supplies, which encompasses what Dungeon World tracks separately as adventuring gear, ammo, rations, and herbs/poultices.

For some games, especially those using OSR systems, decision making around inventory and encumbrance is part of the point. Heck, in Knave, you basically are what you carry. But for other styles of games, this tracking is just tedious and requires too much planning and anticipation, burning time at the table.

For such narrative as opposed to simulationist games, quantum items and abstract gear are a great way to circumvent analysis/paralysis by postponing the decision about what your character is bringing until it is relevant.