How much money can a free game bring in? If your game is "Fortnite," the answer is quite a lot.

The popular video game notched $318 million in revenue last month for maker Epic Games. It was a new high and a 7 percent jump from the game's $296 million haul in April, according to the latest data from SuperData Research, a research firm that tracks the video game industry.

Over the last three months, the game has generated roughly $837 million in revenue.

"Fortnite" is free to play on PCs, Macs, iOS devices and Sony's PlayStation 4, Microsoft's Xbox One and Nintendo's Switch video game consoles. It was the top-grossing game for the month on consoles and the fifth-highest grossing game on PCs.

Consoles drove much of the game's May growth, according to SuperData, with revenues from mobile devices and PCs coming in flat compared with April.

One bright spot for the company's mobile plans: It has yet to release an Android version of the game, though Epic Games says it plans to release one this summer.

Unlike other popular video games such as Activision's "Call of Duty" or Electronic Arts' "Battlefield," "Fortnite" does not charge $59.99 for its game. And as opposed to other free games it also does not include ads. Instead, to generate revenue, it relies on in-game purchases from players to customize their avatars' appearances.

Using its own virtual currency called V-Bucks, players can purchase different axes, dance moves and gliders, which can then be used in the game. One-thousand of these virtual V-Bucks can be purchased for $9.99, with different bundles available, up to $99.99 for 13,500 V-Bucks.

But paying for items does not get you any advantages in "Fortnite." You don't get better weapons, access to new maps or the ability to begin the game in a better location. It is all purely cosmetic, something the company makes clear in its in-game store.

Nonetheless, fans of the game are embracing it.

In a study of 1,000 "Fortnite" players by LendEDU, nearly 69 percent of players spent money on in-game purchases, with the amount spent averaging $84.67.

For roughly 37 percent of spenders, "Fortnite" was the first time they bought something in a video game.