Characters from Apex Legends can be revived and redeployed in battle. (Respawn Entertainment)

Before this week, barely anyone had heard of Apex Legends. It was a project kept so tightly under wraps that when it suddenly launched Monday, it took video gamers completely by surprise — a difficult thing to do in an industry known for its flashy hype and zealous marketing efforts.

But Apex Legends’s stealth approach appears to be working: The game that’s trying to beat Fortnite at its own formula has grown even faster in its opening days than Fortnite itself. In its first three days, Apex Legends racked up 10 million new players, according to its developer; it took two weeks for Fortnite’s player-vs-player game to hit the same mark.

Like Fortnite, Apex Legends is a free-to-play competitive shooter that forces players closer and closer together over the course of a match. It also features vibrantly animated characters that are each unique and have special abilities. But Apex Legends also adds a twist on the battle royal game mode, allowing characters to redeploy if they’re killed, so that players who are killed can stay engaged the whole time. Together with slick movement mechanics and intuitive teamplay, Apex Legends is proving to be an instant hit.

“We knew it would be risky to take the franchise in this direction, to go free to play, and do a surprise launch. But we fell in love with Apex Legends and wanted, needed, other people to play it too,” wrote Vince Zampella, chief executive of developer Respawn Entertainment, in a blog post announcing the 10 million-player milestone.

Part of Apex’s success lies in the fact that almost all of its marketing has been generated by ecstatic players themselves. As part of the launch, the company did establish a live stream of the game on day one. The stream ended up being the most watched on Twitch, according to the Esports Observer. But word-of-mouth has been equally important, with players introducing the game to one another over messaging apps such as Discord.

Respawn has also leaned on game streamers by announcing a $200,000 competitive tournament, which starts Feb. 12 in Europe, followed by a North American match on Feb. 19.

Another aspect of the game’s appeal stems from Respawn’s track record. In 2014, the studio released Titanfall, a fast-paced sci-fi shooter that allows players to go from leaping across rooftops one moment to piloting massive armed robots that drop from the sky in the next. A highly acclaimed sequel followed in 2016. Both were published by Electronic Arts.

Apex Legends takes place in the same fictional universe as Titanfall and features some of the same iconic weaponry and responsive controls.

The game has not been without its share of hiccups; for some time Thursday night, players found they were unable to group up with one another because of an issue with EA’s online platform.

Still, that hasn’t deterred millions from signing up, bolstering Respawn Entertainment’s effort to challenge the genre’s reigning king, Fortnite. The more established game has a much larger registered user base of around 200 million, and roughly 80 million play Fortnite each month. The game has also emerged as a place for gamers to simply hang out with one another, whereas Apex Legends has yet to establish itself as the same kind of nouveau social network.

But at the rate it’s growing, it may not be long before Apex poses a more credible threat.