A gaming device including a plurality of reels with a plurality of symbols on each of the reels. At least one and preferably a plurality of the symbols on the primary reels are designated as tracking or back symbols. A tracking symbol is a symbol that, when generated on a reel, causes the gaming device...http://www.google.de/patents/US7322887?utm_source=gb-gplus-sharePatent US7322887 - Gaming device having sequential activations of a game and replay of previous activations of the game
