When I have gotten the opponents health to zero the game ends even though I still have cards still to attack. I haven't noticed this for players attacking me (and it only happens sometimes but I don't know why).. I.E. they bring my health to less than Zero by a large margin .. if I am trying to complete a 'Damage' Challenge these extra cards would help to finish it but I don't receive these 'Damage' points because the game finishes. Also the same thing happens if the Opponent quits ... they should only be allowed to 'Concede' on their turn as again the 'Damage' points are lost when bad sports 'Concede' after they just play as much as they can even though they know they are going to 'Concede' and wait till you are about to attack.