Gaming machine and method with a persistent symbol modifier feature

A method of operating a gaming machine, the method comprising the operations of:

• presenting, by a presentation assembly, a plurality of symbol-bearing reels, an array, and a modifier indicator;
• and
• accepting, via a value input device, a physical item associated with a monetary value to establish a credit balance;
• conducting, by game-logic circuitry, a first series of spins of the plurality of reels, the symbols borne by the reels including value-bearing symbols, each spin of the first series of spins including spinning and stopping the plurality of reels to land symbols in the array;
• in response to a triggering event, holding any landed value-bearing symbols in place in the array and, conducting, by the game-logic circuitry, a second series of spins of the plurality of reels, the symbols borne by the reels including advancement symbols, each spin of the second series of spins including spinning and stopping the plurality of reels to land symbols in the array, wherein an index indicating one of a plurality of modifiers is incremented each time the landed symbols include an advancement symbol, the modifier indicator indicating the indexed one of the plurality of modifiers;
• and
• at the conclusion of the second series of spins, if the index exceeds a predetermined value, issuing a fixed award, otherwise issuing an award based on the values of the held value-bearing symbols as modified by the indexed one of the plurality of modifiers.

A gaming system comprising:

• a gaming machine including a presentation assembly configured to present a plurality of reels, an array, and a modifier indicator, the plurality of reels bearing a plurality of symbols;
• and
• game-logic circuitry configured to perform the operations of:
• accepting, via a value input device, a physical item associated with a monetary value to establish a credit balance;
• conducting a first series of spins of the plurality of reels, the symbols borne by the reels including value-bearing symbols, each spin of the first series of spins including spinning and stopping the plurality of reels to land symbols in the array, the landed symbols indicating a triggering event when the landed symbols include a predetermined number of the value-bearing symbols;
• in response to the indication of the triggering event, holding the landed value-bearing symbols in place in the array and, conducting a second series of spins of the plurality of reels, the symbols borne by the reels including advancement symbols, each spin of the second series of spins including spinning and stopping the plurality of reels to land symbols in the array, wherein an index indicating one of a plurality of modifiers is incremented each time the landed symbols include an advancement symbol, the modifier indicator indicating the indexed one of the plurality of modifiers;
• and
• at the conclusion of the second series of spins, if the index exceeds a predetermined value, issuing a fixed award, otherwise issuing an award based on the values of the held value-bearing symbols as modified by the indexed one of the plurality of modifiers.