The popular Battle Royale game Fortnite made $2.4 billion for its creator Epic Games in 2018 - despite being free.
That's according to market researchers SuperData, who claimed that Fortnite "generated the most annual revenue of any game in history".
In contrast, arguably one of the most popular paid-for games of 2018 - albeit only available on console - was Red Dead Redemption 2, which pulled-in $516 million during the fourth quarter following its release in October, according to SuperData.
The revenue numbers for Fortnite come as popular video-on-demand service Netflix described Epic Games' Fortnite as one of its prime competitors - over and above direct rivals HBO, Amazon Prime or Hulu.
The company further claimed that it is far less concerned about the launch of Disney+, Disney's new streaming service, than it is about the popularity of Fortnite, which has proved particularly popular among the same teens who Netflix wants to hook-in to its service.
In a letter to shareholders, the company explained that its most-used metric is "consumer screen time" - how much time someone spends in front of their screen with a particular service - and that Fortnite is now stealing far more eye balls than rival video streaming services.
Netflix claims roughly 139 million paying subscribers globally, while Fortnite has more 200 million registered users across PC, Xbox One, PlayStation 4, Nintendo Switch and mobile.
15 January 2019: Flaw in Fortnite authentication could have helped attackers steal player login credentials
Attackers could have used Fortnite security flaw to buy in-game currency on players' stored credit cards
Researchers at security firm Check Point Software used a vulnerability in the online game Fortnite to demonstrate how a security flaw could be used to steal a player's login details.
The method they discovered could have given any attacker the ability to log into a user's Fortnite account without the player being aware of it.
Then, the attacker could gain access to the user's personal information, purchase in-game currency using the victim's stored credit card, retrieve in-game contacts and listen to conversations taking place during game play.
The researchers took advantage of a vulnerability in Fortnite's login process to steal user's authentication tokens.
All an attacker had to do was send a message with a phishing link to a Fortnite player via the Fortnite chat or social media. When the player clicks the link, his Fortnite authentication token will be registered and can be used to log into his account.
The authentication token can be retrieved without the player entering any further login credentials, he only needs to click on the link.
Epic Games, the software developer behind Fortnite, was notified of the security issue before Check Point went public and claims to have fixed it.
Fortnite has been the target of online scams in the past. In one example, a fake website claimed that it would give away Fortnite's in-game currency V-Buck in return for login credentials and personal information.
Check Point has warned players to adopt the same care with Fortnite as they would with any other form of online information. It suggests that players should be careful when sharing information online, and always question the legitimacy of messages - particularly ones bearing attachments or requesting the sharing of personal data.
It also encourages players to use two-factor authentication, which will require them to enter a security code sent to their phone upon login.
Cotton seedling freezes to death as Chang'e-4 shuts down for the Moon's 14-day lunar night
Fortnite easily out-earns PUBG, Assassin's Creed Odyssey and Red Dead Redemption 2 in 2018
Meteor showers as a service will be visible for about 100 kilometres in all directions
Saturn's rings only formed in the past 100 million years, suggests analysis of Cassini space probe data
New findings contradict conventional belief that Saturn's rings were formed along with the planet about 4.5 billion years ago