Inventory constraints

Inventory is a part of the gameplay, and limiting the player’s capability to transport items leads to making choices.
It’s commonly used in RPG, FPS and survival games

-Limitation by size
Diablo, Terraria, Resident evil (1, 2, 3)

-Different items sizes
Diablo

-Different items stacking sizes
Commonly, a stack of items is maxed at 250, for memory use reasons.

-Limitation by weight
Stalker, Eve online, XCom, Ultima online

-No limitation
Final fantasy

Player’s carrying capabilities increase with his progress:
-Bigger bags with more slots
-Higher strength allowing to carry more