
The O’Neill cylinder (also called an O’Neill colony) is a space settlement concept proposed by American physicist Gerard K. O’Neill in his 1976 book The High Frontier: Human Colonies in Space… An O’Neill cylinder would consist of two counter-rotating cylinders. The cylinders would rotate in opposite directions in order to cancel out any gyroscopic effects that would otherwise make it difficult to keep them aimed toward the Sun. Each would be 5 miles (8.0 km) in diameter and 20 miles (32 km) long, connected at each end by a rod via a bearing system. Their rotation would provide artificial gravity.
—“O’Neill cylinder”, Wikipedia article
There’s a new world in VRChat which is attracting a lot of attention! It’s straight out of a science fiction novel: an O’Neill cylinder that is 8 kilometres in diameter and 32 kilometres long, and it features curve gravity, where you can actually run around in a full circle to land up where you started!
(VRChat is not the first social VR platform to feature such a build; I have visited an similar O’Neill cylinder with curve gravity in NeosVR, writing about it here.)
Here’s the original announcement by its creator on Twitter, with the English translation below it, courtesy of the DeepL translator:

The world “Space Colony “Island-4” has been released! It is an enclosed space colony with a diameter of 8km x length of 32km. Please enjoy the huge scale of this cylindrical world!
Space Colony Island-4 is currently one of the most popular worlds in VRChat, so it’s on the VRChat home screen. Here’s a link to the webpage for the world (this page requires a VRChat account to sign in).
By the way, did you know that VRChat has just updated its Quick Menu user interface? Here’s a two-minute video with the highlights of the new design:
Thank you to Rainwolf for the heads-up!