Screenshot via MiYoHo YouTube
The Theater Mechanicus is now available to play in Genshin Impact. To take part, you will need to visit Ruijin in Liyue Harbor. Make sure you complete The Origin of the Lanterns and Liyue: Theater Mechanicus quest to unlock this activity.
There are lots of individual challenges to complete in the Theater Mechanicus that will reward you with Peace Talismans. These can be then be used in the Xiao Shop to purchase items over the course of the Lantern Rite event.
It will cost one Xiao Lantern to play a round of Theater Mechanicus. You can attempt the challenge in either Single Player or Co-Op Mode, but Co-Op only supports two people at once.