The King's Game by Jennifer Scott

Every century, selected individuals are chosen to fight for a chance to reign as a new King in their world. Each selected participants are chosen carefully by their partners and are forced to fight against other contestants for the title of King. Emma, a young secluded girl, was no different. Once she had accepted to be a part of the game, her life is thrown into danger as she must kill to survive. Her world is no longer peaceful as she once knew it to be. She had lost her only family as well as her friend. Her only goal is to win and she is willing to eliminate anyone who gets in her way.