Gaming device with expanding active symbol positions

A method of operating a gaming device comprising a display device, a processor, and a memory storing:

• a plurality of symbol position states, each defining a number of active symbol positions in each of a plurality of columns of symbol positions;
• and
• data defining a plurality of sets of reel strips, wherein each of the plurality of symbol position states corresponds to a set of reel strips from the plurality of sets of reel strips;
• the method comprising:
• upon a trigger condition being met, initiating, by the processor, a series of instances of a feature game, to display the plurality of columns of symbol positions, on the display device, based on a first symbol position state of the plurality of symbol position states;
• in at least a first instance of the feature game, selecting symbols, by the processor, from a first set of reel strips for display in the plurality of columns of symbol positions of the first symbol position state, wherein the first set of reel strips corresponds to the first symbol position state and has a first stack length;
• responsive to an expansion condition being met, updating, by the processor, a current symbol position state to a second symbol position state comprising at least one additional active symbol position relative to the first symbol position state in each of the plurality of columns of symbol positions;
• displaying an animation on the display device showing an expansion of a number of rows corresponding to the at least one additional active symbol position in each of the plurality of columns of symbol positions;
• in at least a subsequent instance of the feature game, selecting symbols, by the processor, from a second set of reel strips for display in the plurality of columns of symbol positions of the second symbol position state, wherein:
• the second set of reel strips corresponds to the second symbol position state and has a second stack length that is smaller than the first stack length;
• and
• a change to symbol selection odds is calculated corresponding to the addition of the at least one additional active symbol position and the change is compensated for using the selection of the symbols from the second set of reel strips as opposed to from the first set of reel strips;
• and
• in each instance of the feature game of the series instances of the feature game, evaluating the selected symbols.

A gaming system, comprising:

• a processor;
• and
• a memory storing:
• a plurality of symbol position states, each defining a number of active symbol positions in each of a plurality of columns of symbol positions;
• data defining a plurality of sets of reel strips including a first set of reel strip, wherein each reel strip of the first set of reel strips has a first stack length defining a number of consecutive reel strip positions and a second set of reel strips, wherein each reel strip of the second set of reel strips has a second stack length shorter than the first stack length, and wherein the plurality of sets of reel strips and their correspondence to symbol position states are arranged such that stack lengths of each other set of reel strips become progressively shorter as a symbol position state is updated;
• and
• instructions which, when executed by the processor, cause the processor to:
• upon a trigger condition being met, initiate a series of instances of a feature game, including by, at the beginning of the series of instances of the feature game, controlling a display to display the plurality of columns of symbol positions based on a first symbol position state of the plurality of symbol position states;
• in at least a first instance of the feature game select symbols from the first set of reel strips for display in the plurality of columns of symbol positions of the first symbol position state;
• responsive to an expansion condition being met, update a current symbol position state to a second symbol position state comprising at least one additional active symbol position relative to the first symbol position state in each of the plurality of columns of symbol positions;
• display an animation on the display showing an expansion of a number of rows corresponding to the at least one additional active symbol position in each of the plurality of columns of symbol positions;
• in at least a subsequent instance of the feature game, select symbols from the second set of reel strips for display in the plurality of columns of symbol positions of the second symbol position state, wherein the processor calculates a change to symbol selection odds corresponding to the at least one added active symbol position and compensates for the change using the selection of the symbols from the second set of reel strips as opposed to from the first set of reel strips;
• and
• in each instance of the feature game of the series of instances of the feature game, evaluate the selected symbols.