Spending real money to play a game of chance for a reward.
"There are monster summons that were introduced with the update that added Ancestor rarity monsters in the game. Monster summons are required to acquire these monsters much stronger than the other rarity monsters, and the items obtained are randomized, so there's no guarantee that you'll get the Ancestor monster you want. The monster acquired from an egg from breeding monsters is also randomized."
"Gacha system has extremely terrible odds when it comes to getting a single car at all. And the rewards that you get for spending 250-500 gold coins sometimes doesn't justify the price, given it requires a premium currency to even have a chance at winning a car. And the resale value of duplicate cars that you've owned are horrendously low."
"This is a "gacha" game. The player pays a large amount of currency or money to have a chance at having the desired item chosen at random."
"While the rewards are always displayed accurately, some in-game items provide random other items, making for an indirect loot box. The Alchemy daily packs are the only ones I saw that have any randomness inherent to the purchase, since they give a range of stones."