YA Sci-Fi - Aliens + Hunger Games?

A friend has asked if I can remember the title of this book, and I’ve searched every possible Google mashup I can think of. (I’m still looking, I’m just stuck.)

They read it 2017-2018, and said it’s either a duology or a trilogy.

“It’s a book about this game run by aliens where a representative from every culture on earth has to come play the game, and the winner ensures that their culture is the only culture that doesn't get destroyed by the aliens, but the aliens are going to kill everybody else in the world.”