A gaming system comprises a gaming machine and game-logic circuitry. The gaming machine includes an electronic display device configured to display an array of symbol positions. The game-logic circuitry is configured to perform the operations of: spinning and stopping symbol-bearing reels to land one or more first value-bearing symbols borne by the reels in the array; animating the array to tag the symbol positions in which the first value-bearing symbols land; again spinning and stopping the symbol-bearing reels to land a second value-bearing symbol borne by the reels in one of the tagged symbol positions; awarding an award based on the value borne by the second value-bearing symbol; and animating the array to untag the one of the tagged symbol positions and any other ones of the tagged symbol positions that are in a cluster with the one of the tagged symbol positions.