Complex sentence: Adam and Eve, respectively--at a time, who will compete in a challenge against the latest person of their gender eliminated; at a predetermined point in the game, the remaining Adam and Eve will return to the game.
Split into simpler sentences: Adam and Eve, respectively--at a time, who will compete in a duel against the latest person of their gender eliminated. At a predetermined point in the game, the remaining Adam and Eve will return to the game.