• Martín Raposo

Types of inventory systems in video games

Updated: Jul 11, 2021

A bit of history

Inventory systems have been around in video games almost since the inception of the industry itself. Perhaps one of its first implementations was in the 70's, with text-based video games. The player had to enter a series of textual commands to perform actions within the game, and thus advance through a story.


In the same way, the RPG (role-playing game) genre was born back in the 80's, which sought to introduce the player into a usually fantasy world, consisting of a number of areas, dungeons and enemies to defeat, obtaining better equipment or items in the path.


It is probably at this point, associated with RPG's, where what we know as inventory becomes popular; a menu or interface within the game that allows the player to store all kinds of items, weapons or resources that are found within it.


The inventory

So, as we saw earlier, an inventory gives the player the ability to store any object or item that is within the game, and that has a relevance to it. It is usually divided into several sections, such as equipment, consumables, resources or collectibles, depending on the target game.

Inventory types

There are as many types of inventory systems as there are designers in the world. But if we could list the most used throughout the history of video games, we would find 5 great types:

  • Unlimited: Allows you to store an infinite amount of items in the inventory. In general, the maximum number to store for each item does have a limit. An example of this inventory system can be Pokémon: LeafGreen (2004):

Pokémon: LeafGreen Inventory
  • By weight: It allows you to store a limited amount of items, assigning each one a specific weight. When the player reaches the maximum weight, a series of consequences will apply, such as a slower movement of the character, or even the inability to move at all, until some items are removed from the inventory, thus reducing the weight. An example can be found in Fallout 4 (2015):

Fallout 4 Inventory
  • By space: This inventory system also has a limit. But unlike the previous one that limits it by weight, this one limits it to a reduced space. The inventory is made up of a set of slots, where each item that the player decides to store will occupy a specific amount of spaces. The player must order the inventory so that he can "fit" all the items he wants to carry. A classic example of this inventory can be found in Resident Evil 4 (2005):

Resident Evil 4 Inventory
  • By slots: Perhaps one of the simplest inventory systems, along with the unlimited one. In this case, it is an inventory with a limit, made up of a series of slots. For each one, the player can store a single item (although he can accumulate them in quantity of the same type). An example of this inventory system is Minecraft (2009):

Minecraft Inventory
  • In-Game: In-Game inventories are not implemented as a menu or interface, but rather as a feature or action within the game itself. They are completely personalized, adapting to the game in question. One of the best examples of this inventory system is the survival title The Forest (2014), where the inventory is the character's own bag/backpack:

The Forest Inventory

Each of these inventory systems can be modified and/or merged, creating unique variations for each video game. The level of realism or fantasy that you want to give to the inventory system comes from the restrictions that apply to it.


Restrictions

When designing an inventory system, be it of any of the types that we saw previously, a series of restrictions and characteristics can be applied that personalize the user experience. For example, some of the most used are:

  • Maximum amount of stack: consists of limiting the amount of items of the same type that can be stacked (accumulated). Generally used in unlimited or slotted inventories. For example, the maximum amount of stack in Minecraft is 64:

  • Compartmentalization: consists of dividing the inventory into compartments; specific sections where only a specific type of item can be stored. For example, an inventory could be divided into the consumables compartment (potions, food, ammunition) and the equipment compartment (only place clothes, suits, armor). A simple example can be the inventory of Rust (2018) with a specific compartment for clothing and armor:

Rust Inventory
  • Expansion: is the ability to acquire more storage capacity for limited inventories, through in-game purchases or unlockables. It is frequently used in types of inventory by weight or by space. In Fallout 4 for example, we can increase the maximum weight capacity to carry. In Resident Evil 4 we can buy more storage lockers.

  • Limitation: consists of establishing limitations by type of item, that is, allowing to store a maximum number of items by type of object in the inventory. It is frequently used in shooters, where it is allowed to store only one primary and one secondary weapon.

  • Durability: consists of giving each item in the inventory a certain durability, which is reduced with a certain number of uses. Upon reaching its minimum value, the item is no longer allowed to be used. It is frequently used in survival titles like Minecraft or Rust.

Item durability in Minecraft (above) and Rust (below)

Summary

Inventory systems tend to go almost unnoticed in video games. Nobody mentions them, or compares them, or promotes them as one more feature of a game. However, players can spend dozens of hours interacting with the same inventory screen and getting used to its use, to such an extent that they become a determining factor in the success of a video game.


A bad inventory design can turn a good game into a nightmare, and a good inventory design can turn a simple game into a hit.


Designing in action

In a future article in this DevLog I will be showing the step-by-step design of a basic survival inventory, and implementing several of its main features.


We hope that this short article has successfully introduced the reader to the main types of inventory, as well as their characteristics and examples.


Thanks for reading,

- Martin. R


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