An electronic gaming machine and method. An initial symbol array of a predetermined size is provided, and reels are used for selecting symbols for display onto the array. There is an active region and a non-active region of the array. At least one reel includes a vertical stack of at least two rows high. If the vertical stack lands in a position overlapping the active and non-active region, the array grows to encompass the vertical stack. The outcome is determined based on the array after it has grown. In addition, a second growing occurs randomly when the vertical stack lands within the active region or overlaps the active and non-active regions.