Patent Publication Number: US-9418506-B2

Title: Electronic gaming machine and gaming method

Description:
BACKGROUND 
     The present invention relates to an electronic gaming machine and in a particular an electronic gaming machine using a base game and a feature game. The invention has been developed primarily for use as an electronic gaming machine and will be described hereinafter by reference to this application. 
     The following discussion of the prior art is intended to present the invention in an appropriate technical context and allow its advantages to be properly appreciated. Unless clearly indicated to the contrary, however, reference to any prior art in this specification should not be construed as an express or implied admission that such art is widely known or forms part of common general knowledge in the field. 
     Conventional gaming machines typically involve awarding prizes to a player according to predetermined combinations of game symbols that appear on an array of game squares displayed on a screen, typically organised into three rows and five columns (a 5×3 array). Other arrays, such as a 3×3 or 4×3, may be used. Each gaming machine randomly selects the game symbols that appear on the array, each column of the array being a “reel”. 
     In an electronic gaming machine, the mechanical reels are replaced with video images of the reels, which are displayed on a video display screen. The electronic gaming machine has an internal electronic game controller, typically a computer, that controls the display of images on the video display screen so that the reels are visibly spun on the screen to simulate a physical reel of a traditional gaming machine. Electronic gaming machines are also more versatile in presenting game information, varying the probabilities for a player to win a prize and varying the type of game that is played. 
     In an electronic gaming machine, the mechanical reels are replaced with video images of the reels, which are displayed on a video display screen. The electronic gaming machine has an internal electronic game controller, typically a computer, that controls the display of images on the video display screen so that the reels are visibly spun on the screen to simulate a physical reel of a traditional gaming machine. Electronic gaming machines are also more versatile in presenting game information, varying the probabilities for a player to win a prize and varying the type of game that is played. Conventionally, such reel-type games comprise a main or base game offered by the electronic gaming machine. 
     Bonus or “feature” games may be provided by an electronic gaming machine in addition to the base or main game. Typically feature games use the same set of reels as the main game and are limited to a set of free games operated under a single set of rules that may be slightly modified from the base game. Once the free feature games have been played, the electronic gaming machine resets itself and returns the player back to the base game. This standard structure to game play limits the variation in the play of the electronic gaming machine. Consequently, it is difficult to retain player interest because there is no apparent incentive for the player to continue playing the same electronic gaming machine once the player becomes familiar with the feature game and the main game. Also, it is difficult to retain player interest since there is little differentiation between gaming machines in terms of the main and feature games that are played. 
     It is an object of the present invention to overcome or substantially ameliorate one or more of the disadvantages of prior art, or at least to provide a useful alternative. 
     It is an object of the invention in at least one preferred form to provide an electronic gaming machine and a method for controlling an electronic gaming machine that encourages player interest. 
     SUMMARY 
     According to a first aspect of the invention, there is provided an electronic gaming machine comprising: 
     a display for displaying a game, wherein said game comprises game symbols arranged into an array of predetermined game positions arranged in rows and columns and where predetermined winning combinations of randomly selected game symbols in said game award prizes to a player, and 
     an electronic game controller for controlling the display of game symbols on said display, 
     wherein the appearance of a first special symbol causes said electronic game controller to select a group of predetermined game positions, said group comprising at least one predetermined game position from at least two of said columns, and 
     wherein each game symbol occupying a predetermined game position in said group is changed into a second special symbol either during a play of said game or at the completion of said play, said change into said second special symbol being visible to said player. 
     Unless the context clearly requires otherwise, throughout the description and the claims, the words “comprise”, “comprising”, and the like are to be construed in an inclusive sense as opposed to an exclusive or exhaustive sense; that is to say, in the sense of “including, but not limited to”. 
     Furthermore, as used herein and unless otherwise specified, the use of the ordinal adjectives “first”, “second”, “third”, etc., to describe a common object, merely indicate that different instances of like objects are being referred to, and are not intended to imply that the objects so described must be in a given sequence, either temporally, spatially, in ranking, or in any other manner. 
     A second aspect of the present invention provides an electronic gaming machine comprising: 
     a housing having a display for displaying a game, wherein said game comprises game symbols arranged into an array of predetermined game positions arranged in rows and columns and where predetermined winning combinations of randomly selected game symbols in said game award prizes to a player; 
     an electronic game controller inside said housing for controlling the display of game symbols on said display; and 
     an input means for receiving commands from said player to operate said electronic gaming machine and initiate play said game on said display, said input means being in electronic communication with said electronic game controller, 
     wherein said electronic game controller in response to a command from said player via said input means commences play of said game by randomly selecting game symbols and transmitting a signal to said display to display said randomly selected game symbols in said predetermined positions on said array, 
     wherein the random selection of a first special symbol to appear in a play of said game shown on said display causes said electronic game controller to select a group of predetermined game positions, said group comprising at least one predetermined game position from at least two of said columns, and 
     wherein said electronic game controller transmits a signal to said display to change each game symbol occupying a predetermined game position in said group into a second special symbol either during said play or at the completion of said play, said change into said second special symbol being visually shown on said display so as to be visible to said player. 
     Preferably, said group comprises all the predetermined game positions in said array. 
     Preferably, wherein said group comprises all the predetermined game positions on said display. In one preferred form, there is a plurality of said arrays on said display, and in this case all the predetermined game positions in each array are selected for the group to be changed into the second symbol. In another preferred form, the array may be extended during game play to add further predetermined game positions. In this case, the further predetermined game positions would also be selected for the group to be changed into the second symbol. It is envisaged that the first symbol can appear on one of the predetermined game positions in one of the arrays or appear on the display and not form part of any of the array(s). 
     Preferably, said first special symbol appears in a predetermined game position of a first column and said group comprises at least one predetermined game position of a second column different to said first column. More preferably, said group comprises the predetermined game positions in said second column. 
     Preferably, said group comprises at least one predetermined game position said first column. In other words, said group comprises at least one predetermined game position in the same column as said first special symbol. In one preferred form, said group comprises all the predetermined game positions in said first column. 
     Preferably, said group comprises the predetermined game position occupied by said first special symbol. 
     Preferably, said group comprises the predetermined game positions in the columns to one side of said first column. In a further preferred form, said one side is to the left of said first column. Alternatively, in another preferred form, said one side is to the right said first column. 
     Preferably, the appearance of said first special symbol in a first and a second predetermined game position causes said electronic game controller to select said group such that said group comprises predetermined game positions located between said first and second predetermined game position. Alternatively, said first special symbol comprises two or more different first symbols such that the appearance of at least two of said different first symbols in a first and a second predetermined game position causes said electronic game controller to select said group such that said group comprises predetermined game positions located between said first and second predetermined game position. In either case, it is preferred that said group comprises predetermined game positions that are also in the same row and/or column as said first predetermined game position or said second predetermined game position. In one preferred form, said group comprises said first predetermined game position and/or said second predetermined game position. 
     Preferably, said group defines a shape on said array. In one preferred form, said shape is rectangular. However, it will be appreciated that other shapes can be formed, including square, triangular or other polygonal shapes, as well as irregular shapes. In an alternative preferred form, said group defines a pattern on said array. In one embodiment of this alternative form, said pattern includes a cross, an X-pattern or other geometrical pattern. 
     Preferably, said group comprises a predetermined portion of said array. More preferably, said predetermined portion comprises a sub-array. In one preferred form, said array comprises an unequal number of rows and/or columns and said sub-array comprises an equal number of rows and/or columns. In another preferred form, said sub-array defines a regular shape on said array. 
     Preferably, said first symbol comprises a substitute symbol. 
     Preferably, said second symbol comprises at least one of said game symbols, a substitute symbol, a symbol that reveals another game symbol and a new game symbol. In one preferred form, said second symbol comprises a symbol that reveals another game symbol. 
     Alternatively, said second symbol is the same as, or has the same effect on said game, as said first special symbol. 
     Preferably, said second symbol comprises two or more different second symbols such that said game symbols from said group change into at least two of said different second symbols. More preferably, one of said at least two different second symbols acts as both a second symbol and as the game symbol it changed from. 
     Preferably, as part of said game, said columns visually move to simulate rotation thereof and said play comprises from when said columns begin to visually move to when said columns stop visually moving. Alternatively, said predetermined game positions individually move visually to simulate rotation of each said predetermined game position. 
     Preferably, said game comprises a jackpot prize. More preferably, said jackpot prize comprises a mystery jackpot. In one preferred form, said game shares said jackpot prize with another game played on said electronic gaming machine. In another preferred form, said game shares said jackpot prize with another game played on a different electronic gaming machine to said electronic gaming machine. 
     Preferably, said electronic game controller is configured to display a base game and/or a feature game on said display. More preferably, said game comprises said base game. Alternatively, said game comprises said feature game. 
     Preferably, the game symbols in said feature game and said base game are arranged in arrays of the same shape or type. Alternatively, said game symbols in said feature game and said base game are arranged in differently shaped arrays. The shapes of said arrays are preferably rectangular, circular, triangular, oval, semi-circular or other non-rectangular shape. 
     Preferably, said electronic game controller causes the display of said feature game in response to said trigger event. Alternatively, said electronic game controller causes the display of said feature game and said base game during play of said base game, said feature game being inactive until triggered. In this preferred form, the change in said feature game from being inactive to active may be indicated on the display. 
     Preferably, said input means comprises a plurality of buttons arranged on a console of said electronic gaming machine. Alternatively or additionally, said input means comprises a touch sensitive surface on said display. 
     Preferably, the electronic gaming machine comprises a mobile electronic gaming device. More preferably, said mobile electronic gaming device comprises a handheld electronic device. Alternatively, said electronic gaming machine comprises a computer. More preferably, said computer is connected to a communication network. 
     According to a third aspect of the invention, there is provided a gaming method for an electronic gaming machine comprising a display and an electronic game controller, the method comprising the steps of: 
     controllably displaying game symbols on said display for playing a game, wherein said game symbols are arranged into an array of predetermined game positions, said predetermined game positions being arranged in rows and columns, and where predetermined winning combinations of randomly selected game symbols award prizes to a player; 
     in response to the appearance of a first special symbol on said display, selecting a group of predetermined game positions, said group comprising at least one predetermined game position from at least two of said columns, and 
     changing each game symbol occupying a predetermined game position in said group into a second special symbol either during a play of said game or at the completion of said play, said change into said second special symbol being visible to said player. 
     A fourth aspect of the present invention provides a gaming method for an electronic gaming machine comprising a housing having a display for displaying a game, wherein said game comprises game symbols arranged into an array of predetermined game positions arranged in rows and columns and where predetermined winning combinations of randomly selected game symbols in said game award prizes to a player; an electronic game controller inside said housing for controlling the display of game symbols on said display; and an input means for receiving commands from said player to operate said electronic gaming machine and initiate play said game on said display, said input means being in electronic communication with said electronic game controller, the method comprising the steps of: 
     said electronic game controller receiving a command from said player via said input means; 
     said electronic game controller commencing a play of said game by randomly selecting game symbols and transmitting a signal to said display to display said randomly selected game symbols in said predetermined positions on said array, 
     said electronic game controller selecting a group of predetermined game positions in response to the random selection of a first special symbol to appear in a play of said game shown on said display, said group comprising at least one predetermined game position from at least two of said columns, and 
     said electronic game controller transmitting a signal to said display to change each game symbol occupying a predetermined game position in said group into a second special symbol either during said play or at the completion of said play, and 
     visually showing said change into said second special symbol on said display so as to be visible to said player. 
     Preferably, said group selecting step comprises selecting all the predetermined game positions in said array. 
     Preferably, said group selecting step comprises selecting all the predetermined game positions on said display. 
     Preferably, said first symbol appears in a predetermined game position of a first column, said group selecting step comprises selecting at least one predetermined game position of a second column different to said first column. More preferably, said group selecting step comprises selecting the predetermined game positions in said second column. 
     Preferably, said group selecting step comprises selecting at least one predetermined game position in said first column. That is, at least one predetermined game position in the same column as said first special symbol is selected. In one preferred form, said group selecting step comprises selecting all the predetermined game positions in said first column. 
     Preferably, said group selecting step comprises selecting the predetermined game position occupied by said first special symbol. 
     Preferably, said group selecting step comprises selecting the predetermined game positions in the columns to one side of said first column. In one preferred form, said group selecting step comprises selecting the predetermined game positions in the columns to the left of said first column. In another preferred form, said group selecting step comprises selecting the predetermined game positions in the columns to the right said first column. 
     Preferably, where said first special symbol appears in a first and a second predetermined game position, said group selecting step comprises selecting predetermined game positions located between said first and second predetermined game position. Alternatively, said first special symbol comprises two or more different first symbols and the method further comprises the step of determining the appearance of at least two of said different first symbols in a first and a second predetermined game position and said group selecting step comprises selecting predetermined game positions located between said first and second predetermined game position. In either case, it is preferred that said group selecting step comprises also selecting predetermined game positions in the same row and/or column as said first predetermined game position or said second predetermined game position. In one preferred form, said group selecting step comprises selecting said first predetermined game position and/or said second predetermined game position. 
     Preferably, said group selecting step comprises selecting predetermined game positions such that said group defines a shape on said array. In one preferred form, said shape is rectangular, square, triangular or other polygonal shape. Alternatively, said shape includes an irregular shape. 
     Alternatively, said group selecting step comprises selecting predetermined game positions such that said group defines a pattern on said array. More preferably, said pattern includes a cross, an X-pattern or other geometrical pattern. 
     Preferably, said first symbol is provided as a substitute symbol. 
     Preferably, said changing step comprises changing said second symbol to at least one of said game symbols, a substitute symbol, a symbol that reveals another game symbol and a new game symbol. Alternatively, said changing step comprises changing said second symbol to said first symbol or a symbol that has the same effect on said game as said first special symbol. 
     Preferably, said second symbol comprises two or more different second symbols and said changing step comprises changing said game symbols from said group into at least two of said different second symbols. More preferably, the method further comprises the step of providing one of said at least two different second symbols to act as both a second symbol and as the game symbol it changed from. 
     Preferably, said method further comprises the step of visually moving said columns as part of said game to simulate rotation of said columns and wherein said play comprises from when said columns begin to visually move to when said columns stop visually moving. 
     Preferably, the method further comprises the step of providing a jackpot prize for said game. More preferably, said jackpot prize comprises a mystery jackpot. In one preferred form, said method comprises the steps of more than one game on said electronic gaming machine and sharing said jackpot prize between at least two of said games. In another preferred form, said method comprises the steps of sharing said jackpot prize between said game and a game playable on another electronic gaming machine. 
     The methods of the third and fourth aspects also preferably have the preferred features of the first or second aspects of the invention not otherwise stated above. 
     According to a fifth aspect of the invention, there is provided a computer system comprising a central processing unit configured for communication with an electronic gaming machine, wherein said computer system is configured to perform the method of the third or fourth aspects of the invention. 
     According to a sixth aspect of the invention, there is provided a computer program configured to perform the method of the third or fourth aspects of the invention. 
     According to a seventh aspect of the invention, there is provided a non-transitory carrier medium carrying computer executable code that, when executed on a central processing unit configured for communication with an electronic gaming machine, causes the central processing unit to perform the method of the third or fourth aspects of the invention. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Preferred embodiments of the invention will now be described, by way of example only, with reference to the accompanying drawings in which: 
         FIG. 1  is a perspective view of an electronic gaming machine according to an embodiment of the invention; 
         FIG. 2  is a schematic drawing of an electronic game controller for the electronic gaming machine of  FIG. 1 ; 
         FIG. 3  is a schematic drawing illustrating a game displayed on an array of the electronic gaming machine of  FIG. 1 ; 
         FIG. 4  is a schematic drawing illustrating a change to the game of  FIG. 3 ; 
         FIG. 5  is a schematic drawing illustrating a game displayed on an array of the electronic gaming machine according to another embodiment of the invention; 
         FIG. 6  is a schematic drawing illustrating a change to the game of  FIG. 5 ; 
         FIG. 7  is a schematic drawing illustrating a game displayed on an array of the electronic gaming machine according to a further embodiment of the invention; 
         FIG. 8  is a schematic drawing illustrating a change to the game of  FIG. 7 ; 
         FIGS. 9 to 18  are schematic drawings illustrating other types of possible changes to the game according to further embodiments of the invention; 
         FIG. 19  is a schematic drawing illustrating a game displayed on an array of the electronic gaming machine according to a further embodiment of the invention; 
         FIG. 20  is a schematic drawing illustrating a change to the game of  FIG. 19 ; 
         FIG. 21  is a schematic drawing illustrating a game displayed on an array of the electronic gaming machine according to yet another embodiment of the invention; 
         FIGS. 22 and 23  are schematic drawings illustrating possible changes to the game of  FIG. 21 ; 
         FIG. 24  is a schematic drawing illustrating a game displayed on an array of the electronic gaming machine according to a further embodiment of the invention; and 
         FIG. 25  is a schematic drawing illustrating a change to the game of  FIG. 21 . 
     
    
    
     DETAILED DESCRIPTION OF THE VARIOUS EMBODIMENTS 
     Referring to  FIG. 1 , an electronic gaming machine  1  according to a first embodiment of the invention includes a cabinet  2 , a console  3  and an internal electronic game controller  4 . The console  3  has various input devices including vending slots  5  for receiving monetary bets and a plurality of buttons  6  for actuation by a player. The vending slots  5  can be configured to receive either cash in the form of banknotes and coins, or credits representing a monetary amount from a memory device, such as but not limited to a memory card, smart card, a radio frequency identification (RFID) device, USB key, magnetic card or other electronic storage device. Typically, the memory device is a credit card, debit card or other card that enables the transfer of monetary credit to the electronic gaming machine  1 . The electronic game controller  4  is generally in the form of a central processing unit, such as a computer, and is in electronic communication with a display in the form of a video display screen  7 , as well as various input devices on the console  3 , as best shown in  FIG. 2 . The electronic game controller  4  will transmit and receive signals to and from each of the input devices and the display  7 . In the case of the vending slots  5 , there may be an intermediate credit verification device that examines and verifies the cash or credits received by the vending slots. Once the cash or credits have been verified by the credit verification device, a signal is sent to the electronic game controller  4 , which then determines whether the minimum bet level has been reached. If so, the electronic game controller  4  will permits play of the game on the electronic gaming machine  1 . If not, the electronic game controller  4  will send a signal to the display  7  to show a message requesting further cash or credits be added to the electronic gaming machine. It is also appreciated that a person skilled in the art would readily understand the location and use of the electronic game controller  4  in the electronic gaming machine  1 . 
     The video screen  7  may also display other standard game information (not shown), including the number of pay lines available, the number of player-selected pay lines, the amount of credits per line, the amount of player credits the amount of the current bet wagered by the player, the amount of wins by the player, a message area, a general menu button and a current denomination button indicating the currently selected base bet denomination. 
     The electronic game controller  4  is programmed to provide a game  8  on the electronic gaming machine  1  for play by a player, as best shown in  FIG. 1 . The game  8  has game symbols  9  arranged into an array  10  in the form of five columns or “reels”  11 , as best shown in  FIG. 3 . While the array  10  is arranged with five columns or “reels”  11  and an even number of rows, it will be appreciated by one skilled in the art that other arrays could be used, such as the industry standard 5×3 or 3×3, 4×3, 5×5, 4×4, etc. Also, the array  10  can have an unequal number of rows and/or columns. The electronic game controller  4  will transmit signals to the display screen  7  to cause the game  8  to be played on the display screen  7 , including showing the game symbols  9 , array  10  and other visible elements of the game  8 , as well as the selection of game positions as discussed in more detail below. 
     The array  10  of the game  8  defines predetermined game positions  12 , in which the game symbols  9  appear. The game or symbol positions  12  are not visually marked by boundary lines and simply provide an area for the game symbols  10  to appear. However, it will be appreciated that in other embodiments, the game positions  12  are defined by visible boundary lines (to define “squares” or game positions) or other markings to define each respective area of the symbol positions. 
     The array  10  is arranged so that a player can select one or more predetermined “pay lines”  13  defined around the array, which correspond to combinations of the game positions  12 . The pay lines  13  correspond to the lines selected by the player and generally comprise at least one game position  12  from each reel  11 . The number of pay lines  13  that can be selected by the player depends on the amount of the monetary bet for playing a game on the array  10 . 
     The game symbols  9  can include a mixture of picture symbols (such as animal symbols, playing card symbols, scatter symbols, wild card symbols and trigger symbols. Those skilled in the art will readily understand that a substitute symbol is able to act as any other game symbol, and hence is also known as a “wild card” symbol. Likewise, those skilled in the art will readily understand that a scatter symbol is a symbol that triggers a game event or confers an award without having to appear on a player-selected pay line  13 . Similarly, a trigger symbol is a symbol that triggers a game event or confers an award, where the trigger symbol may or may not have to appear in combination and may or may not have to appear on the same player-selected pay line  13 . The electronic game controller  4  randomly determines the appearance of the game symbols  9  on the array  10  and then sends an appropriate signal to the display screen  7  to cause the display of the game symbols  9  on the array  10 . 
     The player initially makes a bet using vending slots  5  initiate play of the electronic gaming machine  1  to build up credit to play any of the selectable games on the electronic gaming machine. For example, the player can bet or wager monetary amounts equivalent to a particular amount of credits, depending on the bet denomination selected for the game  8 . Also, the player can make any additional side bets or ante-bets during play of the game  8  once the game has commenced to access additional features in the game, such as increasing the number of winning combinations in the game. 
     Typically, the electronic gaming machine also has a default bet denomination, which is usually the bet denomination that was previously used in the preceding play of the base game  8 . For example, if a person had played the base game  8  with a bet denomination of 5¢, then this would be the default bet denomination for the player when he or she commences play of the game. Where the electronic gaming machine has not yet been played or has been started up, the default bet denomination is initially selected by the electronic game controller  4 . The default bet denomination can be randomly selected or chosen according to a predetermined order. Typically, the electronic game controller  4  will select the bet denomination with the lowest value that is available for the base game  8 , which would be the 1¢ bet denomination for this embodiment. The player may change the bet denomination at any time in the base game  8  by touching the denomination button before or after the reels  11  have spun. 
     The electronic game controller  4  then transmits a signal to the display  7  to cause the reels  11  to appear to visibly rotate or “spin” in a linear path, typically in a downward vertical direction, and randomly display the game symbols  9  in each game position  12 . The electronic game controller  4  also randomly determines the appearance of a special “S” symbol  15  on the display  7 , which in this embodiment is on the array  10 , as best shown in  FIG. 3 . After the reels  11  stop spinning, the electronic game controller  4  determines whether there are any special S symbols  15  on the array  10 . If not, then the electronic game controller  4  determines whether there are any predetermined winning combinations of the game symbols  9  appear in any player-selected pay lines  13 , such as “three of a kind”, “four of a kind” and “five of a kind” and/or other combinations of a “full house”, “straight” or “flush” where the game symbols represent playing cards. It will be appreciated that other winning combinations of game symbols  9  can also be provided. If so, the electronic game gaming machine  1  enters a winning game state and awards a prize according to the displayed predetermined winning combination(s). 
     Where there is the S symbol  15  appears on the array  10 , it causes the electronic game controller  4  to select a group of the game positions  12  where the game symbols  9  are changed into another special “X” symbol  16 , as best shown in  FIG. 4 . The game positions are selected so that at least one game position  12  is selected from a reel  11   a ,  11   c ,  11   d ,  11   e  that is different to the reel  11   b  that contains the S symbol  15 . In this embodiment, the electronic game controller  4  selects the game positions  12  that are in the same row as the special S symbol  15 . The group also includes the special S symbol. 
     The X symbol  16  can act as a substitute (wild), scatter, jackpot or trigger symbol. Alternatively, the X symbol  16  can itself change into another game symbol  9  (for example, an A symbol), including a substitute, scatter, jackpot or trigger symbol. The X symbol  16  can change into a completely new symbol different to the other game symbols, the new symbol conferring a game enhancing element such as a bonus prize or free games. In this embodiment, the X symbols  16  act as substitute or wild symbols. After changing the game symbols  9  to X symbols  16 , the electronic game controller  4  then determines whether winning combinations of game symbols occur on player-selected pay lines  13 . 
     The electronic game controller  4  may also determine the appearance of the scatter symbols in the game  8  (where the X symbol  16  is not a scatter symbol), typically through a random determination. However, it will be appreciated that this determination need not be totally random as the electronic game controller  4  may switch to a reel strip having a greater probability of a scatter symbol appearing where the feature game has not be triggered for a predetermined number of plays of the base game. Also, where a scatter symbol is one of the symbols that are to be changed into the special X symbol  16 , the X symbol retains the function of the scatter symbol. This may be done by providing a hybrid version of the special X symbol to indicate that it functions or acts as both the X symbol and as a scatter symbol. For example, the hybrid X symbol may have the word “scatter” appear underneath the “X” to indicate its dual function. 
     Hence, it can be seen that the player&#39;s interest and excitement in the game  8  will be enhanced once the special S symbol  15  appears as he or she will anticipate the change in other game symbols  9  that are likely to increase the chances of obtaining a winning combination on the array  10 . 
     Another embodiment of the invention is illustrated in  FIGS. 5 and 6 , where corresponding features have been given the same reference numerals. In this embodiment, the appearance of the special S symbol  15  causes the electronic game controller  4  to select all the game positions in the reels to one side of the reel  11   b  in which the S symbol  15  appears, as best shown in  FIG. 6 . In this case the reels  11   c ,  11   d    11   e  to the right of the reel  11   b  have been selected to change the game symbols  9  into the special X symbol  16 . The change to the X symbol  16  has also included the game symbols  9  that occupy the reel  11   b  that has the special S symbol  15 , including the special S symbol itself. However, in another embodiment, only the game symbols  9  in the reels  11   c ,  11   d ,  11   e  to the right of the reel  11   b  are changed into the X symbol  16 . In all other respects, this embodiment works in the same way as the embodiment of  FIGS. 3 and 4  above. 
     A further embodiment is illustrated in  FIGS. 7 and 8 , where corresponding features have been given the same reference numerals. As with the embodiment of  FIGS. 5 and 6 , in this embodiment the appearance of the special S symbol  15  causes the electronic game controller  4  to select all the game positions in the reels to one side of the reel  11   db  in which the S symbol  15  appears, as best shown in  FIG. 8 . However, in this case the reels  11   a ,  11   b ,  11   c  to the left of the reel  11   d  have been selected to change the game symbols  9  into the special X symbol  16 . Again, the change to the X symbol  16  has also included the game symbols  9  that occupy the reel  11   d  that has the special S symbol  15 , including the special S symbol itself. However, in another embodiment, only the game symbols  9  in the reels  11   a ,  11   c ,  11   c  to the left of the reel  11   d  are changed into the X symbol  16 . In all other respects, this embodiment works in the same way as the embodiment of  FIGS. 3 and 4  above. 
     Yet further embodiments are illustrated in  FIGS. 9 to 16 , where corresponding features have been given the same reference numerals. In these embodiments, the appearance of the special S symbol  15  in reel  11   d  (as shown in  FIG. 9 ) causes the electronic game controller  4  to select a group of game positions  12  that define a shape or pattern on the array  10 . In  FIG. 10 , the selected group of game positions  12  that have their game symbols  9  change to the X symbol  16  defines a square shape  20  comprising game positions from reels  11   c  and  11   d . In  FIG. 11 , the selected group of game positions  12  that have their game symbols  9  change to the X symbol  16  defines a triangular shape  21  (or a wedge-like pattern) comprising game positions from reels  11   c  and  11   d . In  FIG. 12 , the selected group of game positions  12  that have their game symbols  9  change to the X symbol  16  defines an X-shape or pattern  22  comprising game positions from reels  11   c ,  11   d  and  11   e . In  FIG. 13 , the selected group of game positions  12  that have their game symbols  9  change to the X symbol  16  defines a cross pattern  23  comprising game positions from reels  11   c ,  11   d  and  11   e . In  FIG. 14 , the selected group of game positions  12  that have their game symbols  9  change to the X symbol  16  defines an extended cross pattern  24  comprising game positions from reels  11   a ,  11   b ,  11   c ,  11   d  and  11   e . In  FIG. 15 , the selected group of game positions  12  that have their game symbols  9  change to the X symbol  16  defines a T-shape or pattern  25  comprising game positions from reels  11   c ,  11   d  and  11   e . In  FIG. 16 , the selected group of game positions  12  that have their game symbols  9  change to the X symbol  16  defines an extended T-shape or pattern  26  comprising game positions from reels  11   a ,  11   b ,  11   c ,  11   d  and  11   e . It will be appreciated that the possible shapes and/or patterns are not limited to those illustrated in the Figures and that other polygonal shapes and/or geometrical patterns can be obtained depending on the various permutation of selected game positions  12  and the size of the array  10 , and even include irregular shapes and/or patterns. For example, each of the shapes and/or patterns illustrated in  FIGS. 10 to 16  have an alternative “inverted” (mirror image) or rotated (90° clockwise or counter-clockwise) versions that provide additional possible shapes and/or patterns that can be provided in the invention. In all other respects, these embodiments work in the same way as the embodiment of  FIGS. 3 and 4  above. 
     Yet another embodiment is illustrated in  FIGS. 17 and 18 , where corresponding features have been given the same reference numerals. In this embodiment, two special S symbols  15  appear in reels  11   b  and  11   c  and this causes the electronic game controller  4  to select a group of game positions  12  that defines a shape or pattern that is partly defined by or at least has the game positions containing the S symbols, as best shown in  FIG. 18 . In this case, a rectangular shape  30  is selected due to the relative positions of the S symbols  15  in  FIG. 17  in which each of the game symbols  9  in the selected game positions  12  are changed into X symbols  16 . It will be appreciated that other shapes or patterns will result depending on the relative positions of the special S symbols  15 . For example, any one of the shapes and/or patterns described in  FIGS. 10 to 16  above can be readily applied to this embodiment. In all other respects, this embodiment works in the same way as the embodiment of  FIGS. 3 and 4  above. 
     A further embodiment of the invention is illustrated in  FIGS. 19 and 20 , where corresponding features have been given the same reference numerals. This embodiment is unlike the other previously described embodiments as the special S symbol  15  does not appear on the array  10  of the game  8 , but instead appears elsewhere on the display  7 . In this case, the appearance of the special S symbol  15  triggers the electronic game controller  4  to randomly select game positions  12  from the array  10  from at least two of the reels  11   a ,  11   b ,  11   c ,  11   d ,  11   e  to be changed into the special X symbol  16  (not shown). Alternatively, all of the game positions  12  are selected to be changed into the special X symbol  16 , as best shown in  FIG. 20 . In all other respects, this embodiment works in the same way as the embodiment of  FIGS. 3 and 4  above. Alternatively, the special S symbol  15  can appear in one of the game positions  12  of the array  10 . 
     The advantage of the embodiment is that once the player sees the appearance of the special S symbol, he or she knows that all the game symbols  9  in the array  10  will change to the same special X symbol  16 , resulting in a win for the maximum possible amount using the special X symbol. Hence, the player&#39;s interest and excitement in the game  8  will be enhanced once the special S symbol  15  appears as he or she will anticipate the change of all the game symbols  9  to the X symbol  16 , thus maximising the winning combination on the array  10 . Where the special X symbol  16  is a substitute symbol, it will confer the highest possible prize obtainable on the game. 
     Another embodiment of the invention is illustrated in  FIGS. 21 to 23 , where corresponding features have been given the same reference numerals. In this embodiment, there are multiple arrays  10  that either form part of the same game  8  or are separate games played independently. In either case, the appearance of the special S symbol  15  in one of the game positions  12  or on the display  7  causes the electronic game controller  4  to randomly select game positions  12  from each of the other arrays  10  to be changed into the special X symbol  16 , in addition to all the game positions  12  in the array where the special S symbol appears changing to the special X symbol, examples of which are shown in  FIGS. 22 and 23 . The selected game positions  12  may be from at least two reels of each array  10 , from one or more of the reels in each array (as best shown in  FIG. 22 ) or confined to all but one or more of the arrays (an example of which is shown in  FIG. 23 ). In one preferred application, all of the game positions  12  from each array  10  are selected so that all the symbols are changed into the special X symbol. In all other respects, this embodiment works in the same way as the embodiment of  FIGS. 3 and 4  above. 
     Yet another embodiment of the invention is illustrated in  FIGS. 24 and 25 , where corresponding features have been given the same reference numerals. In this embodiment, the array for the game  8  comprises an unequal number of rows and columns—that is, neither the number of rows nor the number of columns are equal, since the rows have either two or three game positions and the columns have either two or three game positions. This effectively divides the array into two sub-arrays  10   a  and  10   b . Sub-array  10   a  comprises three rows and three columns of reels  11   c ,  11   d  and  11   e , whereas the smaller sub-array  10   b  comprises two rows and two columns of reels  41   a  and  41   b . Despite the unequal number of rows and columns in the array, the pay lines  13  extend across both sub-arrays  10   a ,  10   b  as in a standard array  10 , as best shown in  FIG. 24 . The distinct shape of the sub-array  10   a  provides a convenient means for showing a selected group of game positions  12  that have their game symbols  9  change into the X symbol  16 , as best shown in  FIG. 25 . Hence, the appearance of the special symbol  15  at the lowermost corner game position  12  of the sub-array  10   a  causes the game symbols  9  in all the game positions  12  of the sub-array  10   a  to change into the X symbol  16 . Thus, it can be seen that the sub-array  10   a  provides a visually appealing indicator as to the group of game positions  12  thus selected to change their respective game symbols. Moreover, it can be seen that the sub-array  10   a  illustrates one of the shapes or patterns that form a square shape as previously contemplated above. In all other aspects, this embodiment also works in the same way as the embodiment of  FIGS. 2 to 4  above. 
     While the preferred embodiments have described as including the special S symbol  15  as one of the game symbols that are changed into the special X symbol  16 , it will be appreciated that in other embodiments the S symbol  15  does not form part of the selected group which are changed into the X symbol  16 . Similarly, while the preferred embodiments in  FIGS. 3 to 18  have been described as the selecting some of the game positions  12  in the array  10  in which their associated symbols  9  are changed into the special X symbol, it will be appreciated that the selection can be modified so that all the game positions  12  in the array are selected to form the group. 
     In one preferred form, there is more than one type of special S symbol  15 , so that where two different types of special S symbols appear on the array two groups of game positions  12  are selected. For example, the special S symbol  15  in  FIG. 5  could be displayed as a “right” S symbol (such as adding to the S symbol the word “right” or an image representing the right like an arrow, pointer or the like directed to the right) to indicate that it causes the selection of the game positions  12  to the right of the reel  11   b  the “right” S symbol appears in. Likewise, the special S symbol  15  in  FIG. 7  could be displayed as a “left” S symbol (such as adding to the S symbol the word “left” or an image representing the left like an arrow, pointer or the like directed to the left) to indicate that it causes the selection of the game positions  12  to the left of the reel  11   d  the “left” S symbol appears in. The appearance of the “left” and “right” S symbols at the same time results in selection of two groups of game positions  12 ; one group to the left of the “left” S symbol and another group to the right of the “right” S symbol, which may result in all the game positions  12  in the array being selected for change. 
     Similar to the special X symbol  16 , in a further embodiment the special S symbol  15  may also have another function, such as being a substitute or wild symbol, scatter symbol, trigger symbol, jackpot symbol or the like. 
     In another preferred form, the individual game positions  12  each represent a single “reel” so that the 5×3 array  10  in  FIG. 3  has 15 separate reels instead of 5 reels. In this case, the invention would function in the same way, with the electronic game controller  4  selecting reels instead of game positions  12  for the group in which the displayed game symbol  9  is changed into the special X symbol  16  in response to the initial appearance of the special S symbol  15  on the array  10 . 
     In a further preferred form, the electronic game controller  4  determines winning combinations of the game symbols  9  at the conclusion of the spin of the reels  11  before determining whether the special S symbol  15  has appeared on the array and thus changing the selected group of game symbols into the special X symbol  16 . In this embodiment, the player is given a second chance to obtain winning combinations of game symbols for a single spin of the reels  11 . This embodiment adds to the player&#39;s excitement and thus retains his or her interest in playing the game  8  on the electronic gaming machine  1 . 
     In yet another preferred form, the electronic game controller  4  does not wait for the all the reels to stop spinning before making a determination as to the appearance of a special S symbol  15 . Instead, the electronic game controller  4  initiates selection of the group once the special S symbol  15  appears on the array  10  before the reels  11  stop spinning. This preferred form can heighten the player&#39;s anticipation while waiting for the reels  11  to stop spinning. 
     While the embodiments in  FIGS. 3 to 16, 24 and 25  have been described in relation to the appearance of a single special S symbol  15 , it will be appreciated that more than one special S symbol can appear on the array  10 . In this case, the selection of the group of symbols to be changed will be made for each special S symbol  15  and the determination of winning combinations of symbols will be based on both groups. Where there is an overlap in the selected game positions  12 , the groups will simply merge together. Likewise, although the embodiment in  FIGS. 17 and 18  has been described in relation to two special S symbols  15 , it will be appreciated that more than two special S symbols can appear on the array  10 . In this case, the group is selected such that the shape or pattern includes the special symbols  15 , and so may be rectangular, square or other polygon shape, or even be of irregular shape. 
     It will also be appreciated that the invention may be applied to either a main or “base” game or a feature game offered on the electronic gaming machine. Alternatively, the invention can be applied to both the base game and a feature game. In this case, the electronic game controller  4  controls the display so that during play of the base game on the array and in response to a trigger event, the electronic game controller  4  causes a feature game (not shown) to be displayed on the array. In one embodiment, the use of special S and X symbols  15  and  16  can be an additional feature of the base game that is accessible upon the player can making an additional side bet or ante-bet during play of the game  8   
     The feature game may employ the same array as the base game, as well as the same game symbols  9  that are used in the base game. However, it will be appreciated that the array for the feature game may vary from the base game. For example, the feature game could adopt a different format of game positions and/or use an entirely different set of game symbols, or a mixture of game symbols from the base game and different game symbols. 
     Where the feature game adopts a reel-type format as illustrated in  FIG. 3 to 18 or 24 and 25 , it typically comprises a predetermined number of free plays or spins of the reels  11 . That is, the reels  11  in the feature game are spun without requiring the player to make a bet, unlike the base game. It will be understood by those skilled in the art that free spins are commonly referred to as “free games”. The number of free spins remaining in the feature game is typically indicated on the screen  7  by a suitable counter (not shown). In the feature game, predetermined winning combinations of randomly selected game symbols  9  result in the award of prizes to the player, usually of an enhanced value compared to the prizes awarded in the base game. 
     The video display screen  7  may also include a top screen, either as a separate display or integrated into the display screen  7 , which provides jackpot information in the form of a major jackpot information box and a minor jackpot information box. The top screen ensures that the jackpot information is available to the player at all times during play of the electronic gaming machine  1 . 
     In other preferred forms, the game  8  has other features like jackpot prizes. The jackpot prize can be shared with any other games offered on the electronic gaming machine (as in multi-game gaming machined) or games offered on separate electronic gaming machines. Information relating to the jackpot prize(s) can be provided on the screen  7  or via a top screen that is devoted to displaying jackpot information. In one preferred form, the jackpot prize comprises a mystery jackpot. That is, none of the symbols in the game trigger the jackpot; hence the triggering event is a “mystery”. By way of comparison, a standard jackpot is typically symbol driven in that a particular combination of symbols must occur in the game to trigger the standard jackpot. 
     Also, in a further preferred form, the player can selectively stop spinning of the reels  11 , either individually or collectively, to increase player interaction. Furthermore, the player can start spinning of the reels  11 , either individually or collectively, to further enhance player interaction. 
     In the preferred embodiments, the video display screen  7  is a touch screen for use as an alternative to or in addition to the player-actuatable buttons  6 . This enables the player to select various features, such as responding to any messages or requests issued on the electronic gaming machine  1  by the electronic game controller  4 . In this case, the player may control when the reels  11  start spinning and stop spinning in any of the games  8  by simply touching the relevant reel  11 . 
     It will be appreciated that while the preferred embodiments have been described in relation to an industry standard electronic gaming machine, the invention can be readily applied to other types of electronic gaming machines, including a personal computer (standing alone or connected to a communications network, LAN or WAN), mobile electronic devices (such as handheld or portable electronic devices like smart phones and tablets) and other electronic devices capable of displaying a game. In the case of a mobile electronic device, in one arrangement it may permit the player to make bets using “virtual” credits that represent a monetary value, but does not require the player to make a monetary transaction. Instead, the invention may provide a tiered access to the various features of the game so that the player can make relatively small payments to access particular features of the game or obtain additional benefits during game play. An alternative arrangement would require the player to purchase virtual credits or tokens via an interface on the mobile electronic device or an online interface accessible by the mobile electronic device. Similarly, either of the above described arrangements can be applied where the invention is implemented on a personal computer (PC) connected to the internet (wirelessly or not). In one example of the implementation, the PC would access an online casino over the internet to play the game of the invention or the game of the invention would be part of a social networking website. It is also contemplated that the player could also make regular payments to subscribe to continue playing the game on the mobile electronic device, PC or other electronic device. 
     In an alternative embodiment, the electronic gaming machine also provides an option for the player to play with either credits based on a monetary amount or virtual credits as discussed above. This can be implemented by way of a selection menu prior to playing the selected game or by providing a suitable menu button on screen during play of the selected game. 
     In another aspect, the invention includes a computer program configured to perform the invention. In this way the invention can be implemented in various ways on an electronic gaming machine. In a further aspect, the invention includes a computer system comprising a central processing unit configured for communication with an electronic gaming machine to perform the invention. In a yet another aspect, the invention includes a non-transitory carrier medium carrying computer executable code that, when executed on a central processing unit configured for communication with an electronic gaming machine, causes said central processing unit to perform the invention. In this case, the non-transitory carrier medium includes an external hard drive, a memory device, including a memory card, smart card, a radio frequency identification (RFID) device, USB key, magnetic card or other electronic storage device. 
     It will further be appreciated that any of the features in the preferred embodiments of the invention can be combined together and are not necessarily applied in isolation from each other. For example, the use of the special symbols  15  and  16  can be a side or ante-bet feature of a base game can be combined with the provision of a separate feature game. 
     By providing special symbols that change into other special symbols that result in the increase chance of obtaining winning combinations of game symbols, the invention increases the player&#39;s excitement and heightens his or her anticipation of a higher prize. This retains player interest and encourages the player to continue playing the various games on the same electronic gaming machine. All these advantages of the invention result in the player being more likely to retain interest in continuing to play the same electronic gaming machine. Furthermore, since the electronic game controller controls operation of the electronic gaming machine, the invention can be readily implemented to existing gaming machines and other gaming systems. In all these respects, the invention represents a practical and commercially significant improvement over the prior art. 
     Although the invention has been described with reference to specific examples, it will be appreciated by those skilled in the art that the invention may be embodied in many other forms.