https://www.pcgamer.com/activision-blizzard-earned-more-than-4-billion-on-in-game-purchases-in-2017/

Activision earned $7 billion in net revenues in 2017, which is an awfully impressive number, although maybe not all that surprising surprising given the games in its stable: Overwatch, Hearthstone, World of Warcraft, and a few others you may have heard of. But what's really interesting (or potentially terrifying, depending on your perspective) is that more than half of that amount—over $4 billion—comes from in-game purchases. 

The bulk of that amount is delivered via King and its Candy Crush games, Candy Crush Saga and Candy Crush Soda Saga, which were number one and two among the top-ten grossing games on the iOS and Android app stores in 2017. But it was hardly alone, as Blizzard (I know, what a surprise) was able to deliver more than $2 billion in revenue without having to actually make a new game.