Patent ID: 8517814

Claim:
A gaming system, comprising a display and a game controller arranged to: select a plurality of first symbols from a set of symbols for play of a game; control the display to display a plurality of the first symbols in one or both of rows and columns; determine a number of second symbols that a player is entitled to, based on at least one triggering criteria; allow the player to select at least one of the originally selected first symbols to be replaced by a second symbol for each second symbol that the player is determined to be entitled to; select at least one second symbol to replace the at least one originally selected first symbol as selected by the player, wherein the second symbols only form winning combinations with other second symbols, and wherein at least one prize is a special prize only winnable when a winning combination formed by the second symbols occurs; control the display to display the second symbol in place of one of the originally selected symbols; and award one or more prizes to the player based on one or more winning combinations formed by the first symbols and the second symbols.