A gaming device displays a symbol matrix including a plurality of symbol positions and at least two symbol staging areas, each symbol staging area including at least one supplemental symbol potentially shiftable into the symbol matrix. The gaming device displays a symbol staging area indicator. For a play of a game, the gaming device generates a symbol in each symbol position of the symbol matrix. Upon an occurrence of a triggering condition, the gaming device indicates one of the symbol staging areas using the symbol staging area indicator and removes at least one symbol from at least one symbol position of the symbol matrix. The gaming device re-populates the empty symbol positions by shifting any appropriate symbols of the symbol matrix any appropriate empty symbol positions, and thereafter shifting at least one supplemental symbol from the indicated symbol staging area into at least one remaining empty symbol position.