Book about teenagers from different ancient civilizations fighting each other to save their own civilization from destruction

• Ancient aliens visited civilizations (Olmec, Minoan, Maori) all over the globe and technologically advanced them. In return, the aliens told the civilizations to put their descendants in a death tournament

• The teens are taught various skills unique to that civilization and how to fight

• Rules of the tournament, the last man standing has their civilization is spared while the rest who died have theirs destroyed

• I think there’s at least 12 civilizations fighting each other, I don’t remember

Edit: the book series is called Endgame: Rules of the Game