Roblox players experienced problems for more than 11 hours, with issues first reported late on Tuesday.
The platform is the world’s largest user-generated games site, and is thought to have about 210 million monthly players.
Roblox said its website, mobile app, Xbox app and games were all affected.
The firm posted on Twitter that it was aware some people were having issues and the team was “actively working on it”.
Hi everyone, we are aware that some of you are having issues accessing Roblox. Our team is actively working on it. Thanks for your patience
— Roblox (@Roblox) May 4, 2022
Reports on Downdetector, a site that tracks outages, suggest problems began just after 23:00 BST on 3 May.
At its peak, the site received more than 1,000 reports of issues, though some users say services are now returning.
Roblox seems to be slowly loading as of 7:30 AM EST, meaning games and pages are loading & errors are in the progress of being fixed. We could see the site come back up completely soon. ✅
— RTC (@Roblox_RTC) May 4, 2022
Data from tracking firms suggests Roblox has on average more than 210 million monthly players, most of whom are children.
Players use core building components to create and share online worlds that anyone can explore.
It is free to play, relying on purchases paid for in currency known as robux.
The company has not yet responded to a BBC request for comment or explained the cause of the problems.