AU2009202160A1 - A System and Method for Gaming - Google Patents

Description

AUSTRALIA Patents Act 1990 COMPLETE SPECIFICATION Standard Patent Applicant (s): Aristocrat Technologies Australia Pty Limited Invention Title: A System and Method for Gaming The following statement is a full description of this invention, including the best method for performing it known to me/us: P74427.AU PatSet_Fdling AWcation 2009-5-26.doc (S) -2 A SYSTEM AND METHOD FOR GAMING Field of the Invention s The present invention relates to a gaming system, a method of gaming, a game controller and computer program code. Background to the Invention 10 It is known to provide a gaming system which comprises a game controller arranged to randomly display several symbols from a predetermined set of symbols and to determine a game outcome such as a game win based on the displayed symbols. Such gaming systems may commonly be 15 implemented as a stepper machine provided with reels with each reel carrying several symbols of the set, or a video machine wherein selected symbols are displayed on virtual reels on a video display. 20 It is also known to provide a "WILD" symbol. A "WILD" symbol is a symbol which can substitute for any other symbol. For example, if a player requires five (5) "KING" symbols to form a winning combination, then a combination of four (4) KING symbols and one (1) WILD symbol also 25 forms a winning combination, because the WILD symbol operates to "substitute for" (i.e. is equivalent to) the KING symbol. In other words, the player perceives the WILD symbol as 30 being a symbol that provides the player with an "extra chance" to receive a favorable game outcome (a win). While the use of WILD symbols is one feature used to gain and maintain player interest, there is a need to find new and different ways to capture and maintain player interest. 35 -3 Summary of the Invention In a first aspect, the invention provides a method of gaming comprising providing an additional game that s operates independently of a main game, wherein the outcome of the additional game operates to vary a sub-set of symbols in the main game responsive to a variance criterion being met, to thereby affect a game outcome in the main game. 10 The game outcome in turn may affect the probability of a prize being awarded. That is, the game outcome is compared against prize data to determine whether a prize is due to a player. 15 In an embodiment, the variance criterion is that a symbol displayed in the additional game is also displayed in the main game. 20 In an embodiment, the variance criterion is that an amount wagered in the main game meets or exceeds a specified wager amount. The variance criterion may alternatively be that an ante bet has been wagered in the main game to thereby activate the additional game. 25 In one embodiment, the outcome of the additional game is at least one symbol that operates to transform like symbols displayed in the main game to another symbol, so as to affect an outcome of the main game. The like 30 symbol(s) may, for example, be transformed into substitute or "WILD" symbols. In an embodiment, the symbol(s) displayed in the additional game is/are randomly selected from a subset of 35 symbols displayable in the main game.

- 4 In an embodiment, the total number of each type of symbol available for selection in the additional game may be a function of a bet amount selected in the main game. Alternatively, a combination of the type of symbol and the 5 total number of symbols may be utilised. The additional game may be played at the conclusion of the main game, prior to commencement of the main game, or during the main game. 10 In an embodiment, the symbol(s) in the additional game are displayed in a reel format. In a second aspect, the invention provides a game 15 controller for a gaming system, the game controller arranged to provide an additional game that operates independently of a main game, wherein the outcome of the additional game operates to vary a sub-set of symbols in the main game responsive to a variance criterion being 20 met, to thereby affect a game outcome in the main game. In an embodiment, the variance criterion is that a symbol displayed in the additional game is also displayed in the main game. 25 In an embodiment, the variance criterion is that an amount wagered in the main game meets or exceeds a specified wager amount. The variance criterion may alternatively be that an ante bet has been wagered in the main game, to 30 thereby activate the additional game. In an embodiment, symbols displayed in the main game which correspond to symbols displayed in the additional game are transformed into a substitute or "WILD" symbol. 35 -5 In an embodiment, the symbol(s) displayed in the additional game is/are randomly selected from a subset of symbols displayable in the main game. s In an embodiment, the total number of each type of symbol available for selection in the additional game may be a function of an amount wagered in the main game. Alternatively, a combination of the type of symbol and the total number of symbols may be utilised. 10 The additional game may be played at the conclusion of the main game, prior to commencement of the main game, or during the main game. 15 In an embodiment, the symbol(s) selected for display in the additional game are displayed in a reel format. In an embodiment, the controller includes a display module operable to cause a representation of the main game and 20 additional game to be displayed on a gaming terminal. In accordance with a third aspect of the present invention, there is provided a gaming system comprising a game controller arranged to control play of a main game 25 and an additional game that operates independently of the main game, such that an outcome of the additional game operates to vary a subset of symbols displayed in the main game responsive to a variance criterion being met, to thereby affect an outcome of the main game; and a display 30 operable to display a representation of the main game and additional game. In a fourth aspect, the invention provides computer program code which when executed by a processor implements 35 a method in accordance with the first aspect of the invention.

- 6 In a fifth aspect the invention provides a computer readable medium comprising the program code in accordance with a fourth aspect of the invention. 5 In accordance with a sixth aspect the present invention comprises transmitting or receiving a data signal comprising the computer program code in accordance with the fourth aspect. 10 Brief Description of the Drawings A preferred embodiment of the invention will now be described in relation to the following drawings in which: 15 Figure 1 is a block diagram of the core components of a gaming system; Figure 2 is a perspective view of a gaming machine; 20 Figure 3 is a block diagram of the functional components of a gaming machine; Figure 4 is a block diagram representing the structure of a memory; 25 Figure 5 is a diagram schematic of a networked gaming system; Figure 6 is a further block diagram of the gaming system; 30 Figure 7 is a flowchart of a method in accordance with an embodiment of the invention; and Figures 8a, 8b and 8c are diagrams depicting examples of a 35 reel-type game in accordance with an embodiment of the invention.

- 7 Description of an Embodiment An embodiment of the present invention provides a gaming system implementing a main game and an additional game. 5 The additional game operates independently of the main game but has the effect of varying a sub-set of symbols in the main game in response to a variance criteria being met, to thereby effect the outcome of the main game. The variance criteria may, for example, be that a symbol 10 displayed in the additional game corresponds to a symbol displayed in the main game, such that the corresponding symbol in the main game is transformed into another symbol such as a substitute or "WILD" symbol. 15 The gaming system may be provided in a number of different forms. In a first form, a stand alone gaming machine is provided wherein all or most components required for implementing 20 the game are present in a player operable gaming machine. In a second form, a distributed architecture is provided wherein some of the components required for implementing the game are present in a player operable gaming machine 25 and some of the components required for implementing the game are located remotely relative to the gaming machine. For example, a "thick client" architecture may be used wherein part of the game is executed on a player operable gaming machine and part of the game is executed remotely, 30 such as by a gaming server; or a "thin client" architecture may be used wherein most of the game is executed remotely such as by a gaming server and a player operable gaming machine is used only to display audible and/or visible gaming information to the player and 35 receive gaming inputs from the player.

- 8 However, it will be understood that other arrangements are envisaged. For example, an architecture may be provided wherein a gaming machine is networked to a gaming server and the respective functions of the gaming machine and the s gaming server are selectively modifiable. For example, the gaming system may operate in stand alone gaming machine mode, "thick client" mode or "thin client" mode depending on the game being played, operating conditions, and so on. Other variations will be apparent to persons 10 skilled in the art. Irrespective of the form, the gaming system comprises several core components. At the broadest level, the core components are a player interface 50 and a game controller 15 60 as illustrated in Figure 1. The player interface is arranged to enable manual interaction between a player and the gaming system and for this purpose includes the input/output components required for the player to enter instructions and play the game. 20 Components of the player interface may vary from embodiment to embodiment but will typically include a credit mechanism 52 to enable a player to input credits and receive payouts, one or more displays 54 and a game 25 play mechanism 56 that enables a player to input game play instructions. The game controller 60 is in data communication with the player interface and typically includes a processor 62 30 that processes the game play instructions in accordance with game play rules and outputs game play outcomes to the display. Typically, the game play instructions are stored as program code in a memory 64 but can also be hardwired. Herein the term "processor" is used to refer generically 35 to any device that can process game play instructions in accordance with game play rules and may include: a microprocessor, microcontroller, programmable logic device -9 or other computational device, a general purpose computer (e.g. a PC) or a server. A gaming system in the form of a stand alone gaming 5 machine 10 is illustrated in Figure 2. The gaming machine 10 includes a console 12 having a display 14 on which is displayed representations of a game 16 that can be played by a player. A mid-trim 20 of the gaming machine 10 houses a bank of buttons 22 for enabling a player to 10 interact with the gaming machine, in particular during game play. The mid-trim 20 also houses a credit input mechanism 24 which in this example includes a coin input chute 24A and a bill collector 24B. Other credit input mechanisms may also be employed, for example, a card 15 reader for reading a smart card, debit card or credit card. A player marketing module may be provided having a reading device may also be provided for the purpose of reading a player tracking device, for example as part of a loyalty program. The player tracking device may be in the 20 form of a card, flash drive or any other portable storage medium capable of being read by the reading device. A top box 26 may carry artwork 28, including for example pay tables and details of bonus awards and other 25 information or images relating to the game. Further artwork and/or information may be provided on a front panel 29 of the console 12. A coin tray 30 is mounted beneath the front panel 29 for dispensing cash payouts from the gaming machine 10. 30 The display 14 shown in Figure 2 is in the form of a video display unit, particularly a cathode ray tube screen device. Alternatively, the display 14 may be a liquid crystal display, plasma screen, any other suitable video 35 display unit, or the visible portion of an electromechanical device. The top box 26 may also include a display, for example a video display unit, which may be - 10 of the same type as the display 14, or of a different type. Figure 3 shows a block diagram of operative components of 5 a typical gaming machine which may be the same as or different to the gaming machine of Figure 2. The gaming machine 100 includes a game controller 101 having a processor 102. Instructions and data to control 10 operation of the processor 102 are stored in a memory 103, which is in data communication with the processor 102. Typically, the gaming machine 100 will include both volatile and non-volatile memory and more than one of each type of memory, with such memories being collectively 15 represented by the memory 103. The gaming machine has hardware meters 104 for purposes including ensuring regulatory compliance and monitoring player credit, an input/output (I/0) interface 105 for 20 communicating with peripheral devices of the gaming machine 100. The input/output interface 105 and/or the peripheral devices may be intelligent devices with their own memory for storing associated instructions and data for use with the input/output interface or the peripheral 25 devices. A random number generator module 113 generates random numbers for use by the processor 102. Persons skilled in the art will appreciate that the reference to random numbers includes pseudo-random numbers. 30 In the example shown in Figure 3, a player interface 120 includes peripheral devices that communicate with the game controller 101 comprise one or more displays 106, a touch screen and/or buttons 107, a card and/or ticket reader 108, a printer 109, a bill acceptor and/or coin input 35 mechanism 110 and a coin output mechanism 111. Additional hardware may be included as part of the gaming machine 100, or hardware may be omitted as required for the - 11 specific implementation. In addition, the gaming machine 100 may include a communications interface, for example a network card 112. s The network card may, for example, send status information, accounting information or other information to a central controller, server or database and receive data or commands from the central controller, server or database. 10 Figure 4 shows a block diagram of the main components of an exemplary memory 103. The memory 103 includes RAM 103A, EPROM 103B and a mass storage device 103C. The RAM 103A typically temporarily holds program files for 15 execution by the processor 102 and related data. The EPROM 103B may be a boot ROM device and/or may contain some system or game related code. The mass storage device 103C is typically used to store game programs, the integrity of which may be verified and/or authenticated by 20 the processor 102 using protected code from the EPROM 103B or elsewhere. It is also possible for the operative components of the gaming machine 100 to be distributed, for example 25 input/output devices 106,107,108,109,110,111 to be provided remotely from the game controller 101. Figure 5 shows a gaming system 200 in accordance with an alternative embodiment. The gaming system 200 includes a 30 network 201, which for example may be an Ethernet network. Gaming machines 202, shown arranged in three banks 203 of two gaming machines 202 in Figure 5, are connected to the network 201. The gaming machines 202 provide a player operable interface and may be the same as the gaming 35 machines 10,100 shown in Figures 2 and 3, or may have simplified functionality depending on the requirements for implementing game play. While banks 203 of two gaming - 12 machines are illustrated in Figure 5, banks of one, three or more gaming machines are also envisaged. One or more displays 204 may also be connected to the 5 network 201. The displays 204 may, for example, be associated with one or more banks 203 of gaming machines. The displays 204 may be used to display representations associated with game play on the gaming machines 202, and/or used to display other representations, for example 10 promotional or informational material. In a thick client embodiment, game server 205 implements part of the game played by a player using a gaming machine 202 and the gaming machine 202 implements part of the 15 game. With this embodiment, as both the game server and the gaming device implement part of the game, they collectively provide a game controller. A database management server 206 may manage storage of game programs and associated data for downloading or access by the 20 gaming devices 202 in a database 206A. Typically, if the gaming system enables players to participate in a Jackpot game, a Jackpot server 207 will be provided to carry out the accounting in respect of the Jackpot game. A loyalty program server 212 may also be provided. 25 In a thin client embodiment, game server 205 implements most or all of the game played by a player using a gaming machine 202 and the gaming machine 202 essentially provides only the player interface. With this embodiment, 30 the game server 205 provides the game controller. The gaming machine will receive player instructions, pass these to the game server which will process them and return game play outcomes to the gaming machine for display. In a thin client embodiment, the gaming machines 35 could be computer terminals, e.g. PCs running software that provides a player interface operable using standard computer input and output components.

- 13 Servers are also typically provided to assist in the administration of the gaming network 200, including for example a gaming floor management server 208, and a s licensing server 209 to monitor the use of licenses relating to particular games. An administrator terminal 210 is provided to allow an administrator to run the network 201 and the devices connected to the network. 10 The gaming network 200 may communicate with other gaming systems, other local networks, for example a corporate network, and/or a wide area network such as the Internet, for example through a firewall 211. 15 Persons skilled in the art will appreciate that in accordance with known techniques, functionality at the server side of the network may be distributed over a plurality of different computers. For example, elements may be run as a single "engine" on one server or a 20 separate server may be provided. For example, the game server 205 could run a random generator engine. Alternatively, a separate random number generator server could be provided. Further, persons skilled in the art will appreciate that a plurality of games servers could be 25 provided to run different games or a single game server may run a plurality of different games as required by the terminals. In some implementations the game controllers of such 30 gaming machines select symbols by employing a stop determining function that randomly determines the stop position for each reel. For example, if there are five reels, each having twenty symbols, the stop determining function might determine that the stop positions are 35 positions: 3, 13, 7, 9 and 17. The spinning of the reels is then controlled so that each symbol comes to a stop in the same row, typically a predetermined row in a "window" - 14 visible to the player on the display that which corresponds to a player playing a single win line. When a reel stops, the symbols will be in one of a plurality of possible symbol positions for that reel relative to the 5 stop position. Spinning reel type games typically allow a player to select how many win lines of a plurality of win lines they will play in each game - i.e. a minimum of one win line up 10 to the maximum number of win lines allowed by the game. Persons, skilled in the art, will appreciate that in other embodiments, the player may select a number of reels to play. Each win line is formed by a set of symbol positions consisting of one symbol position from each reel. That is is, a predetermined symbol position of each reel is assigned to a win line. The symbol positions that constitute each of the win lines are usually advertised to the player by markings on the display or diagrams showing the symbol positions that correspond to each win line. 20 Some of the win lines will be horizontal or diagonal lines but others may be more complex combinations of symbols. Typically, the win lines will be constituted by symbol positions in the visible window. A game outcome is determined based on the symbols on the win lines and a 25 prize table that specifies awards. FURTHER DETAILS OF THE GAME CONTROLLER The game controller 60 of the preferred embodiment (as 30 previously described with reference to Figure 1) is shown in more detail in Figure 6. It will be apparent that the processor 62 implements a number of modules, namely random number generator module 621, symbol selector module 622, outcome determiner module 623, award determiner module 35 624, sequence monitoring module 625, and display controller module 626 based on data stored in memory 64. Persons skilled in the art will appreciate that not all - 15 modules need be implemented by processor 62. For example, the random number generator module 621 could be implemented by a separate circuit, or by a random number generator server. 5 In the presently described embodiment, the game controller 60 is operable to control play of both a main game in the form of a reel game, and an additional, or supplementary, game which operates independently of the main reel game. 10 The additional game has the effect of varying the outcome of the main game responsive to a variance criterion being met, as will be described in more detail in subsequent paragraphs. 15 Operation of the main game will first be described with reference to Figure 8a. In accordance with the presently described embodiment, the main game is in the form of a reel game. A player places an initial wager which causes a plurality of reels to spin. The symbols which are 20 displayed on the reels after they have come to rest (i.e. are displayed in the reel window) are selected by the symbol selector 622, based on symbol data 641 which specifies the available symbols. The displayed symbols (generated utilising the display 54) are rendered 25 utilising image data 642. The symbols are selected by the symbol selector 622 using a random number obtained from the random number generator 621. The outcome determiner module 623 determines game outcomes and their associated prizes based on the number of win lines the player is 30 playing and the symbol combinations appearing in the reel window. The value of any prizes awarded to the player is determined utilising the game outcomes and prize data 643. Persons skilled in the art will also appreciate that the game outcomes and their associated prizes are displayed on 35 the display 54, which is controlled, at least in part, by the display controller 626.

- 16 An award determiner 624 is employed to keep track of the total award and subsequently to modify the award as more games are played. The total is maintained as total data 644 in memory 64. Thus, after each game the award 5 determiner 624 updates the total data 644 to reflect the current total. The sequence monitor 625 monitors for completion of the sequence and, at the conclusion of the sequence, instructs the award determiner 624 to modify the accumulated total. 10 With reference to Fig 8b, the additional game is in the form of a substitute reel 806. The substitute reel 806 is controlled by a WILD substitute reel module 627 implemented by the game controller 60. In the embodiment 15 described herein, the reel module 627 controls the reel 806 such that it spins independently of the reels displayed in the main game. That is, an additional reel 806, hereinafter referred to 20 as the "sixth reel" (due to the embodiment having a main reel game including five reels) is provided in addition to the main reel game of a gaming machine. In the embodiment, the sixth reel 806 is displayed alongside the reel window 800 of the main game. However, it will be understood that 25 the sixth reel 806 may be displayed in any suitable location, such as, for example, on a video screen above the main reel game. Moreover, the sixth reel 806 may be displayed in any suitable configuration, such as a "vertical" reel, a "horizontal" reel, or as a "wheel" 30 (i.e. a wheel akin to a roulette wheel). In another embodiment, the sixth reel 806 may be remotely displayed (e.g. the sixth reel 806 may be implemented as a roulette-style wheel which is located adjacent to, but not 35 incorporated into, the gaming machine). Such variations are within the purview of a person skilled in the art.

- 17 In the presently described embodiment, the sixth reel includes a set of symbols that are a sub-set of the symbols available for selection (i.e. by the symbol selector 622) in the main reel game. The set of symbols s available for selection and display in the sixth reel game is stored in memory 64 as supplementary symbol data 645. It will be understood that the sixth reel 806 may include any combination of a sub-set of symbols available for 10 selection in the main reel game, or indeed the entire set of symbols displayable in the main reel game. Moreover, the sixth reel may also include other symbols (hereafter "supplementary symbols") not available in the main reel game. For example, the supplementary symbols may include 15 "blank" symbols (i.e. certain spaces on the reel contain no symbol), or alternatively, the sixth reel may provide supplementary symbols which award "instant" prizes, such as a feature game, a jackpot, etc. Such variations are within the purview of a person skilled in the art. 20 The operation of the sixth reel is described with reference to the flowchart of Figure 7. In the embodiment described herein, the spinning of the 25 sixth reel 806 takes place after the reels of the main game have come to a stop. That is, referring to flowchart 700 of Figure 7, a player initiates the main reel game (702). The player is informed of the outcome of the main reel game, and if an award is due to the player, the 30 player is also informed of the award that the player has won as a result of the outcome in the main reel game (704). The sixth reel is then spun, and a substitute symbol is revealed in the centre position 808 of the sixth reel (706). The substitute symbol revealed in the centre 35 position 808 operates to vary the outcome of the main game provided that a variance criterion has been met. In the presently described embodiment, the variance criterion is - 18 that a like symbol appears in the reel window 800 of the main game (708). That is, if the substitute symbol revealed in the centre 5 position 808 of the sixth reel (i.e. the symbol that operates to substitute for the WILD symbol) appears in the initial main game, then each symbol in the main game that accords with the substitute symbol is transformed to a WILD symbol (710). Once the transformation is finalised, 10 the final game outcome is shown to the player, and the award determiner 624 recalculates any awards due to the player (712). A specific example will now be described with reference to 15 the screen shots shown in Figures 8a, 8b and 8c. At Figure 8a, there is shown a conventional 3x5 (15 element) reel game 800. Each of the vertical columns of elements represent a "reel", with each element in each reel being arranged to display a symbol. In the example, the symbols 20 used correspond with the symbols used on a conventional deck of cards (i.e. the numerals 2-9, and the symbols J, Q, K and A). The symbol set also includes a WILD symbol, which operates to substitute for any one of the other symbols. In this example, it is assumed that a player must 25 receive at least three (3) identical symbols in any one row (horizontal) to be awarded a prize. Although it will be understood by persons skilled in the art that any prize winning combination could equally apply depending only on the desired implementation. 30 At Figure 8a, a player has initiated a game (e.g. by placing a wager and selecting a number of pay lines to play), and an initial game outcome is displayed in the main reel game. As can be seen, the "K" (King) symbol 35 appears twice in the centre row (802), and the "Q" (Queen) symbol also appears twice in the centre row (804). In the initial game outcome, the player has not won any awards or - 19 prizes, as there is no combination displayed that would result in an award. At Figure 8b, there is shown a sixth reel 806, which 5 automatically spins when the reel spin of the main game has concluded. On the sixth reel 806 coming to rest, a symbol 808 is displayed in the centre position. In this instance, the symbol displayed in the centre position 808 is a "Q" (Queen) symbol. Therefore, the "Q" Queen symbol 10 substitutes for the WILD symbol in the main game. As such, the gaming system operates to change all "Q" (Queen) symbols in the main game to WILD symbols, resulting in the varied reel window shown in Figure 8c. As 15 the final game outcome is now different from the initial game outcome, the award due to the player is recalculated. According to Figure 8c, it can be seen that by changing the two "Q" symbols in the main game to WILD symbols, a 20 winning combination of four "K" (King) symbols is formed (810), as the WILD symbols (which have substituted for the "Q" (Queen) symbols) operate to substitute for the "K" King symbol. As such, the final game outcome has been varied and as a result an award is now payable to the 25 player. In the embodiment described herein, the sixth reel is spun at the conclusion of every main reel game. However, it will be understood that the sixth reel may be arranged to 30 only spin as required. For example, the sixth reel may only spin at random times, or in response to a particular game outcome in the main reel game. Moreover, in an alternate embodiment, the sixth reel may 35 spin before or during the initial game. That is, the player may be notified of the identity of the WILD symbol before or at the same time as the main game result is - 20 displayed. Optionally, the type of symbols and/or the number of times a particular type of symbol appears on the sixth reel may s be determined by the bet amount placed by the player during the main reel game. In accordance with such an embodiment, the probability of symbols displayed in the main game being substituted for a WILD symbol (thereby increasing the probability of being awarded a prize) may 10 be a function of the bet placed by the player during the main reel game. That is, the higher the bet placed by the player, the higher the probability of the WILD substitute symbol being the "necessary" substitute symbol to vary the game outcome in a manner that results in a player 15 receiving an award. In one example implementation, the probability may be increased by increasing the number of symbols of a particular type on the reel, such that the probability of 20 receiving the most advantageous WILD substitute symbol is increased. By increasing the number of available symbols of a particular type, the probability of a player receiving the most desired symbols is correspondingly increased. Of course, it will be understood that any 25 suitable technique or formula may be utilised to increase the probability of a player receiving a desired WILD substitute symbol (and therefore an additional prize or award). For example, one such technique may be to increase the number of symbols displayed in the sixth reel spin, 30 which in turn increases the likelihood of a corresponding symbol being displayed in the main reel game. Various other techniques would be known to a person skilled in the art. 35 It will be understood that determining the type of symbols that appear on the sixth reel game as a function of the initial bet may be used separately or in conjunction with - 21 other incentive mechanisms, as desired by the game operator. Such variations are within the purview of a person skilled in the art. s As described above, the sixth reel may also include blank symbols. Blank symbols result in no symbols in the main game becoming WILD symbols (i.e. a blank symbol has no effect on the result of the main game). 10 An alternative embodiment to that previously described, may involve the player placing an ante bet during play of the main game in order to allow the additional game to become operational. Equally, the player may be required to wager more than a designated amount in the main game 15 for the additional game to operate. The embodiments described herein advantageously increase player interest and involvement in the game, as the player is aware that they have a "second chance" to affect the 20 game outcome and be awarded a prize, even though they may not have won a prize in the main game. Many gaming systems, such as the exemplary gaming system described herein, implement games that involve a display 25 of spinning reels as part of the display of the outcome of a game. However, persons skilled in the art will appreciate that the invention broadly described herein can be implemented in respect of other forms of games, including card games, ball draw games (e.g. bingo or 30 keno), dice games, and pin and ball games. For example, rather than providing a reel with a number of symbols, a "deck of cards" may be provided, such that each card equates to a symbol in the main reel game. A person 35 skilled in the art would understand that such a concept may also be easily extended to dice games, numbered ball games, or indeed any type of game of chance where markers - 22 with different values/symbols are utilised.

Claims (26)

1. A method of gaming comprising: providing an additional game that operates s independently of a main game, wherein the outcome of the additional game operates to vary a sub-set of symbols in the main game responsive to a variance criterion being met, to thereby affect the game outcome in the main game. 10

2. A method in accordance with claim 1, wherein on the game outcome being varied, the game outcome is checked against prize data to determine whether a prize is due to a player. 15

3. A method in accordance with claim 1 or claim 2, wherein the variance criterion is that a symbol displayed in the additional game is also displayed in the main game. 20

4. A method in accordance with any one of the preceding claims, wherein the variance criterion is that an amount wagered in the main game meets or exceeds a specified wager amount. 25

5. A method in accordance with any one of the preceding claims, wherein the variance criterion is that an ante bet has been wagered in the main game to thereby activate the additional game. 30

6. A method in accordance with any one of the preceding claims, wherein the outcome of the additional game is at least one symbol that operates to transform like symbols displayed in the main game to another symbol. 35

7. A method in accordance with claim 6, wherein like symbols are transformed into a substitute or "WILD" symbol. - 24

8. A method in accordance with any one of the preceding claims, wherein the symbol(s) displayed in the additional game is/are randomly selected from a subset of symbols 5 displayable in the main game.

9. A method in accordance with any one of the preceding claims, wherein the total number of each type of symbol available for selection in the additional game is a 10 function of a bet amount selected in the main game.

10. A method in accordance with any one of the preceding claims, wherein the additional game is played either at the conclusion of the main game, prior to commencement of 15 the main game, or during the main game.

11. A method in accordance with any one of the preceding claims, wherein the symbol(s) in the additional game are displayed in a reel format. 20

12. A game controller for a gaming system, the game controller arranged to: provide an additional game in addition to a main game, the additional game operating independently of the 25 main game, wherein the outcome of the additional game operates to vary a sub-set of symbols in the main game, to thereby affect the probability of a prize being awarded. 30

13. A game controller in accordance with claim 12, wherein the variance criterion is that a symbol displayed in the additional game is also displayed in the main game.

14. A game controller in accordance with claim 12 or 35 claim 13, wherein the variance criterion is that an amount wagered in the main game meets or exceeds a specified wager amount. - 25

15. A game controller in accordance with any one of claims 12 to 14, wherein the variance criterion is that an ante bet has been wagered in the main game to thereby 5 activate the additional game.

16. A game controller in accordance with any one of claims 12 to 15, wherein the outcome of the additional game is at least one symbol that operates to transform 10 like symbols displayed in the main game to another symbol.

17. A game controller in accordance with claim 16, wherein like symbols are transformed into a substitute or "WILD" symbol. 15

18. A game controller as claimed in any one of claims 12 to 17, further comprising a symbol selector arranged to randomly select symbols for displaying in the additional game, from a subset of symbols displayable in the main 20 game.

19. A game controller in accordance with any one of claims 12 to 18, wherein the total number of each type of symbol available for selection by the symbol selector is a 25 function of a bet amount selected in the main game.

20. A game controller in accordance with any one of claims 12 to 19, wherein the additional game is played either at the conclusion of the main game, prior to 30 commencement of the main game, or during the main game.

21. A game controller in accordance with any one of claims 12 to 20, further comprising a display module arranged to display the symbol(s) in the additional game 35 in a reel format. - 26

22. A game controller in accordance with claim 21, wherein the display module is operable to cause a representation of the main game and the additional game to be displayed on a gaming machine. 5

23. A gaming system comprising: a module arranged to control play of a main game and an additional game operating independently of the main game, such that an outcome of the additional game operates 10 to vary a sub-set of symbols in the main game responsive to a predetermined criterion being met, to thereby affect the probability of a prize being awarded; and a display module operable to display a representation of the main game and additional game on a gaming machine. 15

24. Computer program code which when executed by a processor implements the method of any one of claims 1 to 11. 20

25. A computer readable medium comprising the program code of claim 24.

26. Transmitting or receiving the computer program code of claim 24.