“It’s the first time we’ve all been excited to get on and play Xbox together,” says Hickey, a recent graduate from the University of Connecticut in the US who says his friends are getting ready to disperse around the country. “It’s the same as going out and getting a beer or getting a bite to eat with the guys.”

He has company. Fortnite’s 125 million players have made it the highest-grossing free-to-play game in history. Everyone from athletes and celebrities to school-age kids drop onto the game’s brightly coloured maps every day, battling to outlast each match’s 99 other opponents, with many spending money to customise their characters.

In May, the game generated US$318 million in revenue for North Carolina-based Epic Games, according to SuperData Research, beating out other stalwart console games such as Electronic Arts’ Fifa 18 and Activision’s Call of Duty: WWII, which charge for downloads and in-game purchases. That monthly take even topped Pokémon Go at its peak. From January to the end of May, Fortnite pulled in more than US$1 billion, estimates the research firm.

That’s because when gamers fire up the game, they are bringing their real-world wallets with them.

Buying skins and cosmetics such as new character costumes or things like hats, tattoos and weapon appearances let players show their personality and allegiance with friends and online competitors. In a study of 1,000 Fortnite players by online lending marketplace LendEdu, nearly 69 per cent made in-game purchases, averaging US$84.67 each.

“It’s almost like younger players are treating Fortnite skins like action figures,” says Carter Rogers, a principal analyst at SuperData. “It has really become a part of the culture to have the latest skin, the latest fashion.”

The cash windfall from players buying custom outfits like a basketball jersey or a hip dance move is the most successful example of a new trend in online gaming. In the past, gaming publishers have sold in-game features, sales that allowed players to reach higher levels or unlock characters. But these short cuts brought controversy.

Last year’s Star Wars: Battlefront II game from Electronic Arts drew the anger of gamers for a system that encouraged paying to unlock characters like Darth Vader or Luke Skywalker over unlocking them more naturally through the game’s progression.

With Fortnite, players don’t get better at vanquishing their opponents by acquiring a new outfit or getting better weapons, they just look different – something that has only heightened the allure of the game.

It is already on the way to a national US obsession, particularly with teens and tweens. The popularity of Fortnite has caused schools and teachers to complain students are sneaking it into class and playing on their phones. Epic Games added a warning to the game’s loading screen cautioning students to set the screens aside.

Dance moves or “emotes” that players can purchase, some of which are copied from rap artists, have become such a hit they’re showing up during major sporting events.

During the recent World Cup Final between France and Croatia, France’s Antoine Griezmann celebrated his goal by doing the “Take the L” dance, a move that has been popularised by Fortnite.

For some players buying a skin is their way to show appreciation to Epic Games for making the game free.

Shana Wilcox, who posts her Fortnite exploits on YouTube under the username “SharkysHood”, has only spent US$30 on the game. The 33-year-old was never a big player of shooting games, yet has enjoyed playing Fortnite.

She has only bought one skin, an Easter-bunny suit known as the “Bunny Brawler”, partly because it was “really cute” and partly from the enjoyment the game has given her.

“I have so much fun playing, that it was like ‘okay, the least I can do is buy a skin that I really, really want,’” she says.

To frequent players of the game, having a skin can also be seen as a virtual sign that you are not a rookie, or “noob”, in the game.

Preston Otterson, a 24-year radio host, has been playing Fortnite for close to six months, lured into the game by its free aspect.

At first, he didn’t spend anything. But after getting called out online by his friends for being a “no skin” – an insult to players who are just using the game’s free, standard avatars – he decided to put some money into it.

“I have spent probably around US$80 which is more than I’ve ever spent on a video game,” Otterson says, adding that he used the cash to purchase outfits, dances and axes. These can cost from US$5 for an entry-level bundle to US$20 for a skin.

And given the enjoyment they’ve got from the game, players say buying a feature like wings or a glider is worth it.

“I pay US$15 a month for Netflix, US$10 a month for Hulu and I play more Fortnite than I watch either Netflix or Hulu,” says Hickey, who sometimes sports the skin of a plant-based supervillain named Flytrap. Once he rationalised it like that, it “wasn’t too much money to spend”.

Cody Sipe, a special investigator for a company that does background checks for the government, uses Fortnite to connect with his younger brothers.

Sipe, 24, and his brothers are scattered across the US, one of whom is in military training in California and another about to go off to college in Florida.

“We’re all guys, we don’t really call each other on the phone very often,” Sipe says. “We bond over either being on the same team or joking about who has the worst stats [in the game] … who has the cooler looking outfits and stuff like that.”

Like in other online games, players can chat and communicate using a headset plugged into their controllers, though not all sessions are full of talk.

“Sometimes we’ll sit on there for an hour and only share, like, 10 words because we are busy playing a game,” Sipe says.

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As for his purchases, Sipe says he will drop a few bucks on a skin or outfit if he thinks it looks cool. One of his favourites: as part of a US$5 bundle, he bought a “Wingman” skin, a Top Gun-like outfit similar to the jumpsuit sported by Tom Cruise in the popular 1986 movie.

“I had a moment of weakness where I was like, ‘Hell yeah, I want to look like Tom Cruise in Top Gun,” so I bought it,” he says with a laugh.