This holiday season, children firing up new videogames will encounter one of the industry’s most contentious moneymaking tactics in years: the “loot box,” an in-game reward that is also for sale.

Like packs of baseball cards, loot boxes hold a random assortment of mostly generic though sometimes rare virtual goodies such as decorative weapons and souped-up skills. They are doled out to players who accomplish certain tasks, or they can be purchased with in-game virtual currency usually for the equivalent of $1 or $2 a pop.

...