Activision Blizzard said that Zombies Chronicles drove monthly active player growth for Call of Duty: Black Ops III, a two-year old game. The boost in the second quarter ended June 30 showed the value of live operations, or launching new content that boosts existing games.

The company reported that news as part of its second quarter earnings, which beat Wall Street’s expectations. (Activision reported non-GAAP revenues of $1.63 billion and earnings per share of 55 cents, compared to expectations of $1.22 billion in revenues and 30 cents a share in non-GAAP earnings). During that quarter, the video game giant launched only one new game, Crash Bandicoot N.Sane Trilogy, on the very last day of the quarter on June 30.

But the results were strong because of Zombies Chronicles, as well as growth for existing games such as Overwatch, Hearthstone, and Black Ops III. Black Ops III has a cult following among Call of Duty fans, who are still playing it faithfully. By contrast, last year’s Call of Duty: Infinite Warfare — which took the annual combat franchise into science fiction and space — wasn’t that popular by comparison.

Activision made the choice to cater to the fans by coming up with new content for the zombies co-op play in Black Ops III, and that led to an increase in monthly active users for that game. But overall, monthly active users for Activision were 47 million, down slightly from a year ago. That suggests that Black Ops III’s results couldn’t make up for Infinite Warfare’s weakness.

Activision is launching Call of Duty: WWII from Sledgehammer Games on November 3. Preorders for that game are high, said Coddy Johnson, chief operating officer at Activision Blizzard, in an earnings call. The Zombies mode for WWII is the “most-liked trailer ever,” he said.

The Zombies Chronicles content came in year two of Black Ops III’s life, the first time Activision has released such content so long after a Call of Duty launch. It drove purchases of that specific piece of content, as well as higher engagement and add-on revenues for Black Ops III.