This is Core's "hub world," a central space for users to congregate and teleport to other games. The base environment was the result of a close, multi-iterative collaboration amongst the entire Environment team - primarily myself, Josh Michael Tyler, Anna Hegyaljai, and Sasha Rassvet, with additional support from Evan Gaugh and concepts by Jordan Louie. Since initial launch it has been re-themed regularly to support holidays and other Core events, as shown in later images.
https://www.artstation.com/joshmtyler
https://www.artstation.com/flashyraccoon
https://www.artstation.com/sasharassvet
https://www.artstation.com/evangaugh
https://www.artstation.com/jordanlouie