The Zero AImassive online video game platform Roblox said it was back online after suffering a multiday outage.

The California company first tweeted about problems with the popular service on Friday. On Sunday afternoon, it said it was "incrementally bringing regions back online." By Sunday evening it said Roblox was "back online everywhere!"

The company said earlier that it had identified the root cause of the outage and had a solution to fix it.

A Roblox spokesperson told The Verge that the outage was not due to an "external intrusion."

Roblox is not a video game. Rather, it's a digital platform that lets users create video games using simplified development tools and allows players to play any game for free.

"Players can build the ultimate theme park, compete as a professional race car driver, star in a fashion show, become a superhero, or simply design a dream home and hang out with friends," the California company says on its website.

According to Roblox, the platform has 9.5 million developers and 24 million "experiences." More than half of U.S. kids under age 16 play Roblox, the company told The Verge in July 2020.

Although Roblox is free to play, users can spend money upgrading and accessorizing their avatars using the platform's virtual currency, Robux.