Interest in Fortnite was so great that in 2018, ripple effects were felt in the sales of gaming hardware and headsets, said Mat Piscatella, a video games analyst for the NPD Group. It was even played on Ellen DeGeneres’s talk show, a marker of mainstream approval.

But Mr. Piscatella noted that past gaming cornerstones like World of Warcraft and Guitar Hero eventually eroded. “Games pop up and change the landscape for a while, and then kind of settle in or fade away,” he said. “We’re into that settling phase with battle royale.”

“A genre like that is the hottest thing in the world until it’s not,” he added.

Analysts say the battle royale market has plateaued, and viewership numbers on streaming sites like Twitch are settling. The genre remains extremely popular, however, and many industry observers are optimistic about its future because it can be easily grafted onto existing properties.

When Call of Duty: Black Ops 4 was released in October, it featured a new battle royale mode. Battlefield V and Fallout 76 unveiled their spins on the genre this year , months after the base games were released.