AU2008252033A1

AU2008252033A1 - A method of gaming, a gaming system and a game controller

Info

Publication number: AU2008252033A1
Application number: AU2008252033A
Authority: AU
Inventors: Sek Hwan Joung
Original assignee: Aristocrat Technologies Australia Pty Ltd
Current assignee: Aristocrat Technologies Australia Pty Ltd
Priority date: 2007-12-05
Filing date: 2008-12-02
Publication date: 2009-06-25
Also published as: US20090221353A1; US20120289307A1

Description

AUSTRALIA Patents Act 1990 COMPLETE SPECIFICATION Standard Patent Applicant(s): Aristocrat Technologies Australia Pty Limited Invention Title: A METHOD OF GAMING, A GAMING SYSTEM AND A GAME CONTROLLER The following statement is a full description of this invention, including the best method for performing it known to me/us: P74124.AU.2 PatSetFing AppiIlalIn 2008-12-1.doc (M) -2 Title A METHOD OF GAMING, A GAMING SYSTEM AND A GAME CONTROLLER 5 Field The present invention relates to a method of gaming, a gaming system and a game controller. 10 Background to the Invention Gaming systems are known comprising a game controller arranged to randomly display several symbols from a predetermined set of symbols and to determine a game 15 outcome such as a game win based on the displayed symbols. Such gaming systems may commonly be implemented as a stepper machine provided with reels with each reel carrying several symbols of the set, or a video machine with selected symbols are displayed in virtual reels on a 20 video display. In such gaming systems it is known to provide a bonus game round or a series of bonus game rounds on the occurrence of a trigger event. A bonus game round is provided without 25 charge or otherwise conferring some special benefit to the player over and above the non-bonus game round. While such bonus game round systems provide users with enjoyment, there is a need for alternative gaming systems 30 with different bonus game features. Summary of the Invention In a first aspect, the invention provides a method of 35 gaming comprising: selecting a plurality of symbols for display in a set of display positions on a display in each game round; N:\Melbourne\Caseo\Patent\74000-74999\P74124.AU.2\Specis\P74124.AU.2 CAP.doc 1/12/08 -3 initiating a series of one or more bonus game rounds conferring a special benefit on the player in response to a trigger condition being met; determining a game round outcome of whether to 5 make an award to a player based on each game round; and ending the series of one or more bonus game rounds when less than a designated number of the displayed symbols in a subsequent game round is a bonus game symbol. 10 In an embodiment, the trigger condition is that at least one of the displayed symbols is a bonus game symbol In an embodiment, the designated number is one such that the series ends when none of the displayed symbols in a 15 subsequent game round is a bonus game symbol In an embodiment, the method further comprises selecting the appearance of the bonus game symbol randomly. 20 In an embodiment, the method further comprises causing the disappearance of the bonus game symbol randomly. In an embodiment, the special benefit conferred on the player by the presence of the bonus game symbol is that 25 the next game round is free of charge. In an embodiment, at each display position associated with a bonus game symbol, only the bonus game symbol is displayed. 30 In an embodiment, the bonus game symbol is a wild symbol able to substitute for any of the other displayed symbols in determining the game round outcome. 35 In an embodiment, the bonus game symbols are displayed in conjunction with a normal symbol in the same display position. N:\Melbourne\Case6\Patent\74000-'14999\P74124.AU.2\Specis\P74124.AU.2 CAP.doc 1/12/08 - 4 In an embodiment, the method comprises determining a displacement of each bonus game symbol relative to the bonus game symbol's current display position such that if 5 the displacement is to a display position within the set of display positions the series of bonus game rounds continues and if the displacement is not to one of the set of display positions and there are less than a designated number of bonus symbols after the displacement, the series 10 of bonus game rounds ends. In an embodiment, the displacement is randomly selected from a set of possible displacements relative to the previous display position. 15 In an embodiment, the set of display positions are a set of reel windows set side by side each comprising a plurality of visible reel positions. 20 In an embodiment, the set of possible displacements is up or down within a reel, left or right between reels or a combination thereof. In an embodiment, the displacement is not randomly 25 selected. In an embodiment, there is more than one bonus game symbol. 30 In a second aspect, the invention provides a gaming system comprising: a display for symbols to be displayed in a set of display positions to a player; a symbol selector arranged to select the symbols 35 for display in each game round; a bonus game controller arranged to: initiate a series of bonus game rounds when a trigger condition is N:\Melbourne\Cases\Patent\74000-74999\P74124.AU.2\Speci\P74124.AU.2 CAP.doc 1/12/08 - 5 met, control the series of one or more bonus game rounds, and end the series of bonus game rounds when less than a designated number of the displayed symbols is a bonus game symbol; and 5 an outcome generator arranged to determine a outcome for each game round. In an embodiment, the bonus game controller is arranged to control the position of each bonus game symbol during the 10 series of one or more bonus game rounds. In an embodiment, the bonus game controller comprises a displacement selector to select a displacement of the bonus game symbol, which depending on the selected 15 displacement, may or may not result in the bonus game symbol being displayed within the set of display positions. In an embodiment, the displacement selector selects the 20 displacements randomly from a set of possible displacements. In an embodiment, the bonus game symbol is a wild symbol able to substitute for any or some of the other displayed 25 symbols in determining the game round outcome. In an embodiment, the trigger condition is that at least one of the displayed symbols is a bonus game symbol 30 In an embodiment, the designated number is one such that the series ends when none of the displayed symbols in a subsequent game round is a bonus game symbol In an embodiment, the special benefit conferred on the 35 player by the presence of the bonus game symbol is that the next game round is free of charge. N:\Melbourne\Cases\Patent\74000-74999\P74124.AU.2\Speci\P74124.AU.2 CAP.doc 1/12/08 - 6 In an embodiment, the set of display positions are a set of reel windows set side by side each comprising a plurality of visible reel positions. 5 In an embodiment, the set of possible displacements is up or down within a reel, left or right between reels or a combination thereof. In an embodiment, at least the game controller is 10 implemented by a processor executing program code stored in a memory. In an embodiment, the gaming system comprises a game play mechanism operable by the player to initiate a play of a 15 game comprising at least one initial game round and any bonus game rounds. In a third aspect, the invention provides a game controller comprising: 20 a symbol selector arranged to select symbols for display to a player in each of a plurality of game rounds; a bonus game controller arranged to initiate a series of bonus game rounds when a trigger condition is met, to control the series of one or more bonus game 25 rounds, and to end the series of bonus game rounds when less than a designated number of the displayed symbols is a bonus game symbol; and an outcome generator arranged to determine a outcome for each game round based on each game round. 30 In an embodiment, the bonus game controller is arranged to control the position of each bonus game symbol during the series of one or more bonus game rounds. 35 In an embodiment, the bonus game controller comprises a displacement selector to select a displacement of the bonus game symbol, which depending on the selected N:\Melbourne\Casea\Patent\74000-74999\P74124.AU.2\Speci\P74124.AU.2 CAP.doc 1/12/08 - 7 displacement, may or may not result in the bonus game symbol being displayed within the set of display positions. 5 In an embodiment, the displacement selector is arranged to select the displacements randomly from a set of possible displacements. In an embodiment, the bonus game symbol is a wild symbol 10 able to substitute for any or some of the other displayed symbols in determining the game round outcome. In an embodiment, the trigger condition is that at least one of the displayed symbols is a bonus game symbol 15 In an embodiment, the designated number is one such that the series ends when none of the displayed symbols in a subsequent game round is a bonus game symbol 20 In an embodiment, the special benefit conferred on the player by the presence of the bonus game symbol is that the next game round is free of charge. In an embodiment, the game controller is implemented by a 25 processor executing program code stored in a memory. In a fourth aspect, there is provided computer program code which when executed by a computer causes the computer to implement the method of the first aspect. 30 In a fifth aspect, the invention provides a computer readable medium comprising the above program code. In a sixth aspect, the invention provides a data signal 35 comprising the above program code. In a seventh aspect, the invention extends to transmitting N:\Melbourne\Cases\Patent\74000-74999\P74124.AU.2\Specis\P74124.AU.2 CAP.doc 1/12/08 -8 the program code. Brief Description of Drawings 5 Figure 1 is a block diagram of the core components of a gaming system. Figure 2 is a perspective view of a stand alone gaming machine; 10 Figure 3 is a block diagram of the functional components of a gaming machine; Figure 4 is a schematic diagram of the functional 15 components of a memory; Figure 5 is a schematic diagram of a network gaming system; 20 Figure 6 is a further block diagram of the gaming system; Figures 7A to 7D show displays of an example; Figure 8 shows a flow diagram for the example. 25 Detailed Description Referring to the drawings, there is shown a gaming system arranged to implement a game wherein a trigger condition 30 such as a bonus game symbol appearing, starts a series of bonus game rounds involving the bonus game symbol. When the bonus game symbol disappears, this ends the series. The gaming system can take a number of different forms. 35 In a first form, a stand alone gaming machine is provided wherein all or most components required for implementing the game are present in a player operable gaming machine. N:\Melbourne\Cases\Patent\74000-74999\P74124.AU.2\Speci\P74124.AU.2 CAP.doc 1/12/08 -9 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 5 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, 10 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 15 receive gaming inputs from the player. 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 20 and the respective functions of the gaming machine and the 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, 25 and so on. Other variations will be apparent to persons skilled in the art. Irrespective of the form, the gaming system comprises several core components. At the broadest level, the core 30 components are a player interface 50 and a game controller 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 35 instructions and play the game. Components of the player interface may vary from N:\Melbourne\CaoeO\Patent\74000-74999\P74124.AU.2\SpeciS\P74124.AU.2 CAP.doc 1/12/08 - 10 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, a game play mechanism 56 that enables a player to input game play 5 instructions (e.g. to place bets), and one or more speakers 58. The game controller 60 is in data communication with the player interface and typically includes a processor 62 10 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 15 to any device that can process game play instructions in accordance with game play rules and may include: a microprocessor, microcontroller, programmable logic device or other computational device, a general purpose computer (e.g. a PC) or a server. 20 A gaming system in the form of a stand alone gaming machine 10 is illustrated in Figure 2. The gaming machine 10 includes a console 12 having a display 14 on which are displayed representations of a game 16 that can be played 25 by a player. A mid-trim 20 of the gaming machine 10 houses a bank of buttons 22 for enabling a player to 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 30 chute 24A and a bill collector 24B. Other credit input mechanisms may also be employed, for example, a card reader for reading a smart card, debit card or credit card. A player marketing module (not shown) having a reading device may also be provided for the purpose of 35 reading a player tracking device, for example as part of a loyalty program. The player tracking device may be in the form of a card, flash drive or any other portable storage N:\Melbourne\Cases\Patent\74000-74999\P74124 .AU.2\Specis\P74124.AU.2 CAP.doc 1/12/08 - 11 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 5 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. 10 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 15 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 of the same type as the display 14, or of a different type. 20 Figure 3 shows a block diagram of operative components of a typical gaming machine which may be the same as or different to the gaming machine of Figure 2. 25 The gaming machine 100 includes a game controller 101 having a processor 102. Instructions and data to control 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 30 volatile and non-volatile memory and more than one of each type of memory, with such memories being collectively represented by the memory 103. The gaming machine has hardware meters 104 for purposes 35 including ensuring regulatory compliance and monitoring player credit, an input/output (I/0) interface 105 for communicating with peripheral devices of the gaming N:\Melbourne\Cases\Patent\74000-74999\P74124.AU.2\Specis\P74124.AU.2 CAP.doc 1/12/08 - 12 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 5 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. 10 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 15 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 specific implementation. 20 In addition, the gaming machine 100 may include a communications interface, for example a network card 112. The network card may, for example, send status information, accounting information or other information to a central controller, server or database and receive 25 data or commands from the central controller, server or database. Figure 4 shows a block diagram of the main components of an exemplary memory 103. The memory 103 includes RAM 30 103A, EPROM 103B and a mass storage device 103C. The RAM 103A typically temporarily holds program files for 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 35 103C is typically used to store game programs, the integrity of which may be verified and/or authenticated by the processor 102 using protected code from the EPROM 103B N:\Melbourne\cases\Patent\74000-74999\P74124.AU.2\Specis\P74124.AU.2 CAP.doc 1/12/08 - 13 or elsewhere. It is also possible for the operative components of the gaming machine 100 to be distributed, for example 5 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 10 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 15 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 machines are illustrated in Figure 5, banks of one, three or more gaming machines are also envisaged. 20 One or more displays 204 may also be connected to the network 201. For example, the displays 204 may be associated with one or more banks 203 of gaming machines. The displays 204 may be used to display representations 25 associated with game play on the gaming machines 202, and/or used to display other representations, for example promotional or informational material. In a thick client embodiment, game server 205 implements 30 part of the game played by a player using a gaming machine 202 and the gaming machine 202 implements part of the 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 35 management server 206 may manage storage of game programs and associated data for downloading or access by the gaming devices 202 in a database 206A. Typically, if the N:\Melbourne\Cases\Patent\74000-74999\P74124.AU.2\Specis\P74124.AU.2 CAP.doc 1/12/08 - 14 gaming system enables players to participate in a Jackpot game, a Jackpot server 207 will be provided to perform accounting functions for the Jackpot game. A loyalty program server 212 may also be provided. 5 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, 10 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 15 could be computer terminals, e.g. PCs running software that provides a player interface operable using standard computer input and output components. Servers are also typically provided to assist in the 20 administration of the gaming network 200, including for example a gaming floor management server 208, and a 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 25 network 201 and the devices connected to the network. The gaming system 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, 30 for example through a firewall 211. 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 35 plurality of different computers. For example, elements may be run as a single "engine" on one server or a separate server may be provided. For example, the game N:\Melbourne\Cases\Patent\74000-74999\P74124.AU.2\Specis\P74124.AU.2 CAP.doc 1/12/08 - 15 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 5 provided to run different games or a single game server may run a plurality of different games as required by the terminals. The game controllers of gaming systems implementing games 10 that involve a display of spinning reels as part of the display of the outcome of the game have a stop determining function that determines the stop position for each reel. For example, if there are five reels, each having twenty symbols, the stop determining function might determine 15 that the stop positions are 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 designated row in a "window", the designated row corresponding to a "single win line" game. When the reels 20 stops, the symbols will be in one of a plurality of possible symbol positions for that reel relative to the stop position. Embodiments of the present invention include gaming 25 systems that 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 to the maximum number of win lines allowed by the game. Each win line is formed by a set of symbol positions consisting of one symbol 30 position from each reel. That 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 35 correspond to each win line. The win lines may be for example, horizontal or diagonal lines. N:\Melbourne\Cases\Patent\74000-74999\P74124.AU.2\Specis\P74124.AU.2 CAP.doc 1/12/08 - 16 The game controller of the preferred embodiment is shown in more detail in Figure 6. The game controller carries out a play of the game in response to a player operating a game play mechanism 56 to place a wager. The game 5 controller carries out an initial game round and, if a trigger condition is met, one or more bonus game rounds. Each game round involves the selection of some fresh symbols. The game controller 60 incorporates a symbol selector 610 that selects symbols using random numbers 10 from random number generator 650 under control of outcome generator 630, including possibly a bonus game symbol, to appear on the display 54. In the embodiment, the appearance of a bonus game symbol in the initial game round initiates a series of one or more bonus game rounds, 15 however other triggers known in the art may be employed such as symbol combination occurring, a turnover elapsing or a system connected to the gaming system triggering the bonus game series. During the series of bonus game rounds, the symbol selector 610 operates to select further sets of 20 game symbols, and the bonus game controller 620 controls, via displacement selector 625, the new position, if any, of the bonus game symbol in the next game, using one of a set of possible displacements from displacement data 646 such that it will replace the symbol selected for that 25 position. If there is more than one bonus symbol, each is controlled. In this embodiment, the choice of displacement is made on the basis of a random number provided by random number generator 650. In another alternative, the displacement is deterministic. The 30 further set of symbols may include a further bonus symbol. The displacement selector may be arranged so that the new position of a bonus symbol cannot overly another bonus symbol. 35 Once the bonus game rounds begin, the player will receive a special benefit for the next game round which in the preferred embodiment is that the next game round is free. N:\Melbourne\Caseo\Patent\74000-74999\P74124.AU.2\Speci\P74124.AU.2 CAP.doc 1/12/08 - 17 Another example of special benefit is that the prize for the next game round is doubled. Another example, is that the persistent bonus game symbol has an additional play characteristic which confers a benefit for example, a wild 5 symbol increases the chances of winning outcomes occurring. The outcome generator 630 includes an outcome evaluator 635 to calculate any prize associated with the current 10 round depending on the game instructions 644 and updateprize data 645 and display 54 on the player interface 50. In the preferred embodiment the bonus symbol is a wild symbol and can substitute for any normal symbol in evaluation of prizes specified by the prize data 645. 15 On completion of the current round, the symbol selector 610 uses random number generator 650 to generate a new symbol set for the next bonus game round and passes control of the bonus game symbol to bonus game symbol 20 controller 620. Bonus game symbol controller 620 determines using displacement selector 625 where and whether on the display positions the bonus game symbol should appear and symbol selector 610 replaces the symbol selected for that location with the bonus game symbol. As 25 in the previous round, the outcome generator 630 calculates the game round outcome and updates prize data 645. The series of bonus game rounds ends when bonus game 30 symbol controller 620 produces a displacement that causes the bonus game symbol to disappear off the set of display positions. In embodiments, where there is more than one bonus game symbol, typically all symbols are required to "disappear" before the series ends. However, alternative 35 embodiments are possible where a minimum number of symbols are required for the series to continue such that the series may end with a bonus symbol still displayed. That N:\Melbourne\Case\Patent\74000-74999\P74124.AU.2\Specis\P74124.AU.2 CAP.doc 1/12/08 - 18 is, the game series is ended when less than a designated number of bonus game symbols is displayed; the designated number may be 1, 2 or more (a value of 1 implying that no bonus game symbols are displayed). Once the bonus game 5 rounds ends, the player places a further wager to initiate another initial game round. The player may be presented with options such as a "gamble" option at the conclusion of the game round and before credits are transferred to the credit meter. 10 In the preferred embodiment, the bonus game symbol is a single symbol and it occupies the space of a normal symbol. In an alternative embodiment, the bonus game symbol appears with a normal symbol in the same position, 15 with both symbols visible. This alternative embodiment allows additional options for the effect of the bonus symbol according to the game instructions 644 on the prize data 645, such as a multiplier for any prize calculated using the normal symbol in the same position. 20 It will be apparent from the above embodiment, that the bonus game round confers a benefit on the player, in the embodiment, that each bonus game round is free and the player has improved opportunities by virtue of the wild 25 symbol. In other embodiments, additional or different benefits may be conferred, for example prizes may be multiplied. During the series of bonus game rounds, random selection 30 of a new display position for the bonus game symbol is made by the new position selector 625. When this selection is made by a displacement based on a set of possible displacements in displacement data 646, the displacement may be restricted to a random choice among the set of 35 possible displacements. For example, a "dance step" such as two positions up and one across. N:\Melbourne\Cases\Patent\74000-74999\P74124.AU.2\Specia\P74124.AU.2 CAP.doc 1/12/08 - 19 The displacement of the bonus game symbols can be displayed in a number of different styles, for example: "walking", "dancing", "jumping" or "sliding" the symbol from one position to the next prior to the reels 5 spinning in the next game; "walking", "dancing", "jumping" or "sliding" the symbol from one position to the next as the reels are spinning in the next game; "walking", "dancing", "jumping" or "sliding" the 10 symbol from one position to the next after the reels have spun in the next game; or visually disappearing as the reels are spun and reappearing as the reels stop spinning. 15 The method 80 of the invention is summarised in Figure 8. The method involves starting the game 810 and determining 820 whether this is a bonus game round. If it is not a bonus game round (as will be the case initially,) the method involves selecting all symbols for display and 20 their positions 830. The method then involves determining the game round outcome 840 and awarding any prizes associated with the game outcome. It is then determined 870 whether one of 25 the symbols that has been selected is a bonus game symbol. If it is a bonus game symbol a series of bonus game rounds is initiated 890 such that in the second iteration, the answer at 820 will be that it is a bonus game round and hence non-bonus symbols will be selected and the new 30 position or appearance of the bonus game round symbol will be determined. The game outcome will then be determined with the method continuing to step 870 where after if one of the symbols is a bonus symbol, the game will continue, otherwise the series of bonus game rounds ends. 35 In an alternative embodiment, an alternative or additional transformation may be applied to the bonus symbol between N:\Melbourne\Cases\Patent\74000-74999\P74124.AU.2\Specis\P74124AU.2 CAP.doc 1/12/08 - 20 game rounds. For example, the colour of the bonus symbol may be changed from red to blue to indicate that it has persisted from a previous round or a set of different bonus symbols may be employed indicative of the longevity 5 of the symbol. Game Round 1 Example Now referring to Figure 7A, a player has purchased a game round or is in an existing series of bonus game rounds and 10 the symbols shown appear on the reels. The display is divided into 5 reels 740a to 740e each displaying 3 symbols in the window, in rows 750a, 750b and 750c. The bonus game symbol marked W indicates that next game round will be a bonus game round. The bonus game symbol W is a 15 wild symbol, enabling substitution with normal symbols, but in this case there are no patterns with any such substitution which the outcome generator 630 determines can win a prize and so the prize data 645 is not updated. 20 Game Round 2 Example This game, following from Game Round 1, is free because the W symbols is in the windom. As shown in Figure 7B, the symbol selector 610 has selected a new set of symbols to display and the bonus game controller 620 has determined 25 using displacement selector 625 a displacement from W of one row down in the same reel, into the centre row, covering the symbol which would have appeared on the fourth reel, centre. The outcome generator 630 awards the prize for four Kings ("K") on the centre row, as if W were 30 a King, and the prize data 645 is updated. Game Round 3 Example This game, following from Game Round 2 where the bonus game symbol still appeared, is still part of the bonus 35 game round series and is free. As shown in Figure 7c, the symbol selector 610 has selected a new set of symbols to display and the bonus game symbol controller has N:\Melbourne\Cases\Patent\74000-74999\P74124.AU.2\Specis\P74124.AU.2 CAP.doc 1/12/08 - 21 determined a new position for the bonus game symbol W in the third reel in the bottom row, a displacement of 1 row down and one reel left from the previous game, covering the symbol which would have appeared on the third reel, 5 lower. There are no patterns with any wild symbol substitution for W which the outcome generator 630 determines can win a prize and so the prize data 645 is not updated. Because the bonus game symbol is still present, the next game round (Game Round 4) will also be 10 free. Game Round 4 Example This game, following from game round 3 where the bonus game symbol still appeared, is still part of the bonus 15 game round series and is free. As shown in Figure 7d, the symbol selector 610 has selected a new set of non-bonus symbols to display and the displacement selector 625 has selected a displacement down one further row, off the display. No symbol positions are replaced and the bonus 20 game symbol will not appear. The outcome generator 630 determines that there are no winning patterns and so the prize data 645 is not updated. Because the bonus game symbol is not displayed, the series of bonus game rounds ends and the next game round will not be free. 25 Persons skilled in the art will appreciate that the method of the preferred embodiment could be embodied in program code. The program code could be supplied in a number of ways, for example on a computer readable medium, such as a 30 disc or a memory (for example, that could replace part of memory 103) or as a data signal (for example, by downloading it from a server). Persons skilled in the art will also appreciate that many 35 variations may be made to the invention without departing from the scope of the invention. In particular, features of the above embodiment and examples may be combined to N:\Melbourne\Cases\Patent\74000-74999\P74124.AU.2\Specis\P74124.AU.2 CAP.doc 1/12/08 - 22 form further embodiments. In the claims which follow and in the preceding description of the invention, except where the context 5 requires otherwise due to express language or necessary implication, the word "comprise" or variations such as "comprises" or "comprising" is used in an inclusive sense, i.e. to specify the presence of the stated features but not to preclude the presence or addition of further 10 features in various embodiments of the invention. N.\Melbourne\Cases\Patent\74000-74999\P74124.AU.2\Specis\P74124.AU.2 CAP.doc 1/12/08

Claims

1. A method of gaming comprising: selecting a plurality of symbols for display in a 5 set of display positions on a display in each game round; initiating a series of one or more bonus game rounds conferring a special benefit on the player in response to a trigger condition being met; determining a game round outcome of whether to 10 make an award to a player based on each game round; and ending the series of one or more bonus game rounds when less than a designated number of the displayed symbols in a subsequent game round is a bonus game symbol. 15

2. A method as claimed in claim 1, wherein the trigger condition is that at least one of the displayed symbols is a bonus game symbol

3. A method as claimed in claim 1 or claim 2, 20 wherein the designated number is one such that the series ends when none of the displayed symbols in a subsequent game round is a bonus game symbol

4. A method as claimed in claim 2, further 25 comprising selecting the appearance of the bonus game symbol randomly.

5. A method as claimed in claim 3, further comprising causing the disappearance of the bonus game 30 symbol randomly.

6. A method as claimed in any one of claims 1 to 5, wherein the special benefit conferred on the player by the presence of the bonus game symbol is that the next game 35 round is free of charge. N:\Me1bourne\Cases\Patent\74000-74999\P74124.AU.2\Specin\P74124.AU.2 CAP.doc 1/12/08 - 24

7. A method as claimed in any one of claims 1 to 6, wherein at each display position associated with a bonus game symbol, only the bonus game symbol is displayed. 5

8. A method as claimed in claim 7, wherein the bonus game symbol is a wild symbol able to substitute for any of the other displayed symbols in determining the game round outcome. 10

9. A method as claimed in any one of claims 1 to 6, wherein the bonus game symbols are displayed in conjunction with a normal symbol in the same display position. 15

10. A method as claimed in any one of claims 1 to 9, comprising determining a displacement of each bonus game symbol relative to the bonus game symbol's current display position such that if the displacement is to a display position within the set of display positions the series of 20 bonus game rounds continues and if the displacement is not to one of the set of display positions and there are less than a designated number of bonus symbols after the displacement, the series of bonus game rounds ends. 25

11. A method as claimed in claim 10, wherein the displacement is randomly selected from a set of possible displacements relative to the previous display position.

12. A method as claimed in claim 10, wherein the set 30 of display positions are a set of reel windows set side by side each comprising a plurality of visible reel positions.

13. A method as claimed in claim 12, wherein the set 35 of possible displacements is up or down within a reel, left or right between reels or a combination thereof. N:\Melbourne\Case\Patent\74000-74999\P74124.AU.2\Speci\P74124.AU.2 CAP-doc 1/12/08 - 25

14. A method as claimed in claim 10, wherein the displacement is not randomly selected.

15. A method as claimed in claim 1, wherein there is 5 more than one bonus game symbol.

16. A gaming system comprising: a display for symbols to be displayed in a set of display positions to a player; 10 a symbol selector arranged to select the symbols for display in each game round; a bonus game controller arranged to: initiate a series of bonus game rounds when a trigger condition is met, control the series of one or more bonus game rounds, 15 and end the series of bonus game rounds when less than a designated number of the displayed symbols is a bonus game symbol; and an outcome generator arranged to determine a outcome for each game round. 20

17. A gaming system as claimed in claim 16, wherein the bonus game controller is arranged to control the position of each bonus game symbol during the series of one or more bonus game rounds. 25

18. A gaming system as claimed in claim 17, wherein the bonus game controller comprises a displacement selector to select a displacement of the bonus game symbol, which depending on the selected displacement, may 30 or may not result in the bonus game symbol being displayed within the set of display positions.

19. A gaming system as claimed in claim 17, wherein the displacement selector selects the displacements 35 randomly from a set of possible displacements.

20. A gaming system as claimed in any one of claims N:\Melbourne\Cases\Patent\74OO-74999\P74124.AU.2\Speie\P74124.AU2 CAP.doc 1/12/08 - 26 16 to 19, wherein the bonus game symbol is a wild symbol able to substitute for any or some of the other displayed symbols in determining the game round outcome. 5

21. A gaming system as claimed in any one of claims 16 to 20, wherein the trigger condition is that at least one of the displayed symbols is a bonus game symbol

22. A gaming system as claimed in any one of claims 10 16 to 21, wherein the designated number is one such that the series ends when none of the displayed symbols in a subsequent game round is a bonus game symbol

23. A gaming system as claimed in any one of claims 15 16 to 22, wherein the special benefit conferred on the player by the presence of the bonus game symbol is that the next game round is free of charge.

24. A gaming system as claimed in any one of claims 20 16 to 23, wherein the set of display positions are a set of reel windows set side by side each comprising a plurality of visible reel positions.

25. A gaming system as claimed in claim 24 wherein 25 the set of possible displacements is up or down within a reel, left or right between reels or a combination thereof.

26. A gaming system as claimed in any one of claims 30 16 to 25, wherein at least the game controller is implemented by a processor executing program code stored in a memory.

27. A gaming system as claimed in any one of claims 35 16 to 26, comprising a game play mechanism operable by the player to initiate a play of a game comprising at least one initial game round and any bonus game rounds. N:\Melbourne\Cases\Patent\24000-74999\P74124.AU.2\Specis\P74124.AU.2 CAP.doc 1/12/08 - 27

28. A game controller comprising: a symbol selector arranged to select symbols for display to a player in each of a plurality of game rounds; 5 a bonus game controller arranged to initiate a series of bonus game rounds when a trigger condition is met, to control the series of one or more bonus game rounds, and to end the series of bonus game rounds when less than a designated number of the displayed symbols is 10 a bonus game symbol; and an outcome generator arranged to determine a outcome for each game round based on each game round.

29. A game controller as claimed in claim 29 wherein 15 the bonus game controller is arranged to control the position of each bonus game symbol during the series of one or more bonus game rounds.

30. A game controller as claimed in claim 29, wherein 20 the bonus game controller comprises a displacement selector to select a displacement of the bonus game symbol, which depending on the selected displacement, may or may not result in the bonus game symbol being displayed within the set of display positions. 25

31. A game controller as claimed in claim 30 wherein the displacement selector is arranged to select the displacements randomly from a set of possible displacements. 30

32. A game controller as claimed in any one of claims 28 to 31, wherein the bonus game symbol is a wild symbol able to substitute for any or some of the other displayed symbols in determining the game round outcome. 35

33. A game controller as claimed in any one of claims 28 to 32, wherein the trigger condition is that at least N:\Melbourne\Cases\Patent\74000-74999\P74124.AU.2\Specis\P74124.AU.2 CAP.doc 1/12/08 - 28 one of the displayed symbols is a bonus game symbol

34. A game controller as claimed in any one of claims 28 to 33, wherein the designated number is one such that 5 the series ends when none of the displayed symbols in a subsequent game round is a bonus game symbol

35. A game controller as claimed in any one of claims 28 to 34, wherein the special benefit conferred on the 10 player by the presence of the bonus game symbol is that the next game round is free of charge.

36. A game controller as claimed in any one of claims 28 to 35, implemented by a processor executing program 15 code stored in a memory.

37. Computer program code which when executed by a computer causes the computer to implement a computer implemented method of gaming of any one of claims 1 to 15. 20

38. A computer readable medium comprising the program code of claim 37.

39. A data signal comprising the program code of 25 claim 37.

40. Transmitting the program code of claim 37. N:\Melbourne\Cases\Patent\74000-74999\P74124.AU.2\Specis\P74124.AU.2 CAP.doc 1/12/08