Battle royale games have now raked in more than $2 billion on Android and iOS, according to the latest data.

Fortnite and competing titles like PUBG Mobile earned an estimated $476 million during the first quarter of 2019 alone. A surprising title leads in player spending — but there is a catch.

Battle royale games have been around for a long time, but they didn’t really take off in a big way until the arrival of Fortnite. Now almost every big franchise, including Call of Duty, has its own battle royale mode.

Many of them have made the leap to mobile, where they are earnings millions of dollars every month. The latest data from Sensor Tower shows that battle royale titles combines have now grossed a total of $2 billion in under two years.

A surprise leader

There’s a surprise leader in Sensor Tower’s estimates. Knives Out, the free-to-play title from NetEase Games, takes the number one spot in player spending with over $643 million. Fortnite takes second place with over $630 million.

PUBG Mobile takes the third spot with almost $439 million, while Garena Free Fire comes in fourth with just over $252 million. Rules of Survival, which was popular before bigger titles came to mobile, has made $96 million.

But there is a big caveat. Sensor Tower’s data for Fortnite only takes into account the amount of money players have spent on iOS. Even if those on Android spent a third of the amount, it would have a sizable lead over rivals.

There’s no stopping battle royale

The battle royale genre shows no signs of slowing down just yet. During the first quarter of 2019, these five titles grossed $476 million in revenue — an increase of almost 63% over the same quarter last year.

Other big battle royale games are on the way to mobile, too.

EA has already hinted that it is working on bringing Apex Legends to Android and iOS, while Activision has confirmed a new Call of Duty game for mobile that will almost certainly have a battle royale mode.