Loot box
Also said as Crate, Random item box, Surprise mechanics
A paid item with a random reward inside, so you pay for a chance at what you want. It runs on the same schedule that keeps people at slot machines, with a game wrapped around it.
Refuse to sell these. Belgium's Gaming Commission found in April 2018 that paid boxes in FIFA 18, Counter-Strike: Global Offensive and Overwatch broke its gambling law. Elsewhere the rules vary and keep changing. Children can buy them. And you have no way of telling a hobbyist from someone who is losing the rent, because the cost has no ceiling.
Say it
“No paid random rewards. If we use a box as a surprise, it is only earned by play. Anything sold for money shows exactly what you get before you pay.”
Where you’ve seen it
Overwatch's original loot boxes held only cosmetics, and even those were found to break Belgian law, so being cosmetic did not save them. Blizzard later dropped paid boxes altogether in Overwatch 2.
Not to be confused with random drop
A random drop you earn by playing costs you time. A loot box costs you money, and that is the line that matters to regulators and should matter to you.