Fortnite fever is still running strong with gamers, many of whom are typically core Call of Duty players. So, as this year’s released—Call of Duty: Black Ops 4—hits shelves, Activision (ATVI) and its developers are meeting the challenge head-on.

Black Ops 4 ditches the single player campaign that has been a hallmark of the series. Instead, the game will focus entirely on multiplayer action, including a mode called “Blackout,” which follows the same Battle Royale rules found in Fortnite (players are dropped into an ever-shrinking area, where the last one alive wins the game).

It’s a battle of gaming juggernauts. (Fortnite hadn’t reached its current level of popularity when last year’s Call of Duty was released.) And there’s a tremendous amount of money on the line. Fortnite is bringing in an average of $1.5 million per day—on iOS devices alone. (The game just launched on Android this week.)

Fortnite might have peaked, though. Viewership on Twitch declined with the release of the game’s sixth season in last September. And that could open a window for Activision.

Engagement for the public beta of Black Ops 4 was high, averaging 103,000 viewers during its limited period. Peak viewership was nearly four times that of last year’s Call of Duty release, according to Ben Schachter of Macquarie Capital.

“Call of Duty would likely be the largest beneficiary of a drop-off in Fortnite as the first holiday’18 AAA release to include a battle royale mode,” he said in a note to investors.

Black Ops 4 developer Treyarch isn’t planning to turn its attentions to its next Call of Duty game anytime soon, either. Dan Bunting, co-studio head says that “this is a game that we plan to support for the long haul.”

That’s the same, incredibly effective strategy Epic Games has used with Fortnite. And it could keep players engaged, and distracted from Fortnite, for some time.