I'm actually a CN Server player of Arknights. You guys are so lucky to have only 6 chapters, because the 7th one is SOOOOOOO DIFFICULT! I'm still stuck at 7-9, but it have 18 in total...
The only reason I join the US Server is because of Nian, as I didn't get her in CN Server (But I have W).
Well, I love the US Server... At least not so difficult... And I have Ch'en and her new clothes...