The hit game "Fortnite" is on pace to become a billion-dollar title in 2018, thanks in no small part to surging use by female gamers.

When Epic Games first released "Fortnite" in 2017, it was only compatible with PCs, the Xbox and PlayStation. Its first version was a pay-to-play game mode known as "Save the World." A few months later, Epic released the free-to-play "Battle Royale" version, which became a viral hit among casual and hardcore gamers.

In April, Epic took a major step toward diversifying its user base when it released "Battle Royale" on iOS, luring people who don't typically play games on consoles or PCs. According to Apptopia founder Jonathan Kay, the game's mobile version is used largely by female gamers, who make up 46 percent of total gamers.

Historically, women have dominated mobile gaming, accounting for 63 percent of the market and 60 percent of gamers who play mobile games daily. Women are 36 percent more likely than men to make in-game purchases on mobile, according to Mediakix.

In its first month in the app store, "Fortnite" had nearly $2 million in daily revenue. According to research firm SuperData, the mobile version has earned $53.1 million in sales in the app store since its launch.

There are 45 million people playing "Fortnite" worldwide today. In April, the game generated $296 million in total revenue, putting it on pace to pull in $3.5 billion.