I disagree with General Zaroff's opinion that Rainsford "hadn't played the game."  Rainsford had no choice but to play the game according to General Zaroff's rules, or so Zaroff thought.  Because the General did not get he wanted, which was Sanger Rainsford's corpse or surrender, when he wanted it, he chose to make an excuse for himself, which was that Rainsford had not played the game; this sort of response to the situation would seem typical of the type of person Zaroff seemed to be (bully, self-centered, egocentric, etc.).  However, Rainsford had clearly played the game and continued to do so until Zaroff's implied demise; Zaroff had formerly set the rules and did not count on his intended quarry's reversal of roles (the hunted became the hunter).  It was apparent throughout the story that Rainsford "played the game," since he had no option to do otherwise.