Yep. It's a seasonal event since Helvetia is a location. It'll last until the 27rd.
The robots celebrate at the top of every hour. Go there, gather ingredients for the celebration (for example: baker needs radtoad eggs to make donuts, candlemaker needs honeybeast wax, butcher needs intestines for sausage and so on...) After helping the robots out they put on paper mache masks and march in a parade, where they'll get attacked by various creatures. Keep em alive, light the bonfire at the end and get rewarded.
You get fasnacht decor plans for your camp, recipes and masks. Some of the masks are super rare.
It's a fun event, but It does get monotonous after you've completed it 30+ times trying to get the mask you want that has a less than a 0.5% chance of dropping.
Neat!
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[teep is] an evil genius who will one day kill us all - Choco teep is a God damn genius - Zodd