Patent ID: 7014559

Claim:
A gaming machine which includes: a display means on which a plurality of display positions are displayed, the display positions being arranged in a predetermined region of the display means; and a game control means arranged to control images displayed on the display means, the control means also controlling playing of a game on the machine, the game comprising a video representation of a plurality of spinning reels, each reel comprising a set of reel symbols wherein a plurality of reel symbols are randomly selected and displayed in the display positions on the display means such that, if a winning combination results, the machine pays a prize, the control means being operable, upon the occurrence of a predetermined triggering event, to generate a series of bonus symbols in a bonus feature game comprising a plurality of rounds, said bonus symbols being substitute symbols arranged to substitute for one or more of the reel symbols; wherein a first bonus symbol in the series is displayed in one display position and is taken into consideration in determining a first award based on at least one payline-based winning combination wherein said winning combination includes at least a first bonus symbol and reel symbols which are not bonus symbols and, thereafter, a second bonus symbol in the series is displayed in at least one other display position without changing the positions of the spinning reel symbols in a subsequent round and the control means further being operable to make a determination, when the first bonus symbol appears at the one display position, whether or not the first bonus symbol is to remain at the one display position as a residual substitute symbol and, if the determination is that the first bonus symbol is a residual substitute symbol, when the second bonus symbol appears at the at least one other display position, both the first bonus symbol and the second bonus symbol are taken into consideration in determining an award based on at least one other payline-based winning combination wherein said winning combination includes at least the first and second bonus symbols and reel symbols which are not bonus symbols; or if the determination is that the first bonus symbol is not to remain at the one display position as a residual substitute symbol when the second bonus symbol appears at the one other display position, the second bonus symbol is taken into consideration in determining an award based on at least yet another payline-based winning combination and the first bonus symbol is not taken into consideration.