Just an idea I’ve been tossing around in my head for a very simple inventory system for an OSR style game, somewhat based on Microlite 74’s inventory system. Characters have one inventory ‘slot’ for each point of Strength (i.e. a character with 13 Str has 13 inventory slots). Each slot is roughly equivalent to 10 lbs, but weight isn’t really tracked in this system, just slots. Every piece of equipment, including weapons and armor, must be accounted for within the available inventory slots.
Many similar smaller items may be combined to take a single slot. For example, 100 coins or 10 gems count as one slot, as would 4 potions or scrolls. Note that backpacks, pouches, sacks and other containers are assumed and don’t even need to be recorded.
The first three slots are reserved for ‘readied’ items, such as weapons, wands, potions, etc. This represents having a weapon or wand tucked into one’s belt for quick access. ‘Readied’ items may be used without using an action to retrieve them from inventory first; items in any other inventory slot require an action to retrieve before they can be used.
For the sake of simplicity, the number of inventory slots should be considered a hard cap. Resist the temptation to let the PCs carry just ‘a little bit more’ in exchange for a reduced movement rate or any other penalty. In this system, a character’s move rate would be determined solely by the type of armor they wear, not their total encumbrance weight. Two or more characters can still co-operate to carry heavy burdens, such as a large treasure chest, for example.