Communication is part of what makes us human, and boy, we have a ton of ways of doing that. But how would aliens communicate, if they even have that concept?
I’m playing fast and loose with the definition of both “alien” and “language” here. The goal is to have a bunch of books with cool science-fictiony linguistic stuff going on as opposed to sticking to rigid definitions.
Also, if a book description doesn’t mention language, it’s because I didn’t want to give away a plot point.