Patent Publication Number: US-2009239632-A1

Title: method of gaming, a game controller and a gaming system

Description:
RELATED APPLICATIONS 
     This application claims priority to U.S. Provisional Patent Application No. 61/015,560 having a filing date of Dec. 20, 2007. 
    
    
     FIELD 
     The present invention relates to a method of gaming, a game controller and a gaming system. 
     BACKGROUND 
     It is known to provide a gaming machine having a spinning reel type game where when a wild symbol appears in a centre position on a centre reel of five spinning reels, the symbols above and below it are changed to be wild symbols and the three wild symbols are used in evaluating the outcome of that spin. In one variation, the wild symbol is displayed as “expanding” so that a single, enlarged wild symbol takes the place of all symbols on that reel. 
     While such gaming systems provide users with enjoyment, a need exists for alternative gaming systems in order to maintain or increase player enjoyment. 
     SUMMARY OF THE INVENTION 
     In a first aspect, the invention provides a method of gaming comprising: 
     generating game outcomes for game rounds by selecting symbols for display at a plurality of display positions on a display, the display positions being divided into a plurality of subsets of display positions and the selection of symbols for each subset of display positions being made from different ones of a plurality of symbol sets; and
 
making a modification to generation of the game outcome for at least one subsequent game round in response to determining that a condition is met, the modification comprising causing a designated set of symbols to be displayed for one of the subsets of display positions while continuing to select symbols for the other subsets.
 
     In an embodiment, the modification is a first modification made in response to a first condition and the method comprises making a second modification to generation of a game outcome for at least one subsequent game round in response to determining that a second condition is met, the second modification comprising causing a second designated set of symbols to be displayed for one of the subsets of display positions. 
     In an embodiment, the subsets are columns of display positions that correspond to respective ones of a plurality of reels such that modifying a game outcome corresponds to replacing a reel with a designated set of symbols. 
     In an embodiment, when symbols are selected for display, they are selected by selecting a stop position for each reel. 
     In an embodiment, the designated set of symbols is displayed as a spinning reel consisting of the designated set of symbols. 
     In an embodiment, each of the designated symbols is a special symbol having an increased play characteristic relative to other symbols. 
     In an embodiment, the special symbol is a wild symbol. 
     In an embodiment, the method comprises making a third modification of generation of a game outcome for at least one subsequent game round in response to determining that a third condition is met, the modification comprising causing a third designated set of symbols to be displayed for one of the subsets of display positions. 
     In an embodiment, the method comprises evaluating for each game round whether the generated game outcome includes one or more winning outcomes. 
     In an embodiment, evaluations are performed in a designated order of symbol sets, and modification occurs in the opposite order. 
     In an embodiment, winning outcomes are evaluated on a left to right basis and reels are replaced right to left. 
     In an embodiment, there are five sets of display positions. 
     In an embodiment, each set of display positions has three display positions. 
     In an embodiment, symbols are selected using a random number generator. 
     In an embodiment, any modification is also applied to the current game round. 
     In a second aspect, the invention provides a game controller for a gaming system, the game controller arranged to: 
     generate game outcomes for game rounds by selecting symbols for display at a plurality of display positions on a display, the display positions being divided into a plurality of subsets of display positions and the selection of symbols for each subset of display positions being made from different ones of a plurality of symbol sets; and 
     modify generation of the game outcome for at least one subsequent game round in response to determining that a condition is met, the modification comprising causing a designated set of symbols to be displayed for one of the subsets of display positions while continuing to select symbols for the other subsets. 
     In an embodiment, the game controller comprises an outcome generator arranged to generate game outcomes. 
     In an embodiment, the outcome generator comprises a symbol selector for selecting symbols. 
     In an embodiment, the outcome generator comprises a modification implementer arranged to cause a designated set of symbols to be displayed. 
     In an embodiment, the modification is a first modification made in response to a first condition and the game controller is arranged to make a second modification to generation of a game outcome for at least one subsequent game round in response to determining that a second condition is met, the second modification comprising causing a second designated set of symbols to be displayed for one of the subsets of display positions. 
     In an embodiment, the subsets are columns of display positions that correspond to respective ones of a plurality of reels such that modifying a game outcome corresponds to replacing a reel with a designated set of symbols. 
     In an embodiment, the when symbols are selected for display, the game controller selects a stop position for each reel. 
     In an embodiment, the designated set of symbols is displayed under control of the game controller as a spinning reel consisting of the designated set of symbols. 
     In an embodiment, each of the designated symbols is a special symbol having an increased play characteristic relative to other symbols. 
     In an embodiment, the special symbol is a wild symbol. 
     In an embodiment, game controller is arranged to make a third modification of generation of a game outcome for at least one subsequent game round in response to determining that a third condition is met, the modification comprising causing a third designated set of symbols to be displayed for one of the subsets of display positions. 
     In an embodiment, the game controller comprises a prize evaluator arranged to evaluate for each game round whether the generated game outcome includes one or more winning outcomes. 
     In an embodiment, evaluations are performed in a designated order of symbol sets, and modification occurs in the opposite order. 
     In an embodiment, winning outcomes are evaluated on a left to right basis and reels are replaced right to left. 
     In an embodiment, there are five sets of display positions. 
     In an embodiment, each set of display positions has three display positions. 
     In an embodiment, the game controller comprises a random number generator employed in selecting the symbols. 
     In an embodiment, modification is also applied to the current game round. 
     In an embodiment, the game controller is implemented by a memory and processor arranged to generate the game outcomes based on program code stored in the memory. 
     In a third aspect, the invention provides a gaming system comprising: 
     a display; and 
     a game controller arranged to: 
     generate game outcomes for game rounds by selecting symbols for display at a plurality of display positions on the display, the display positions being divided into a plurality of subsets of display positions and the selection of symbols for each subset of display positions being made from different ones of a plurality of symbol sets; and 
     modify generation of the game outcome for at least one subsequent game round in response to determining that a condition is met, the modification comprising causing a designated set of symbols to be displayed for one of the subsets of display positions while continuing to select symbols for the other subsets. 
     In an embodiment, the game controller comprises an outcome generator arranged to generate game outcomes. 
     In an embodiment, the outcome generator comprises a symbol selector for selecting symbols. 
     In an embodiment, the outcome generator comprises a modification implementer arranged to cause a designated set of symbols to be displayed. 
     In an embodiment, the modification is a first modification made in response to a first condition and the game controller is arranged to make a second modification to generation of a game outcome for at least one subsequent game round in response to determining that a second condition is met, the second modification comprising causing a second designated set of symbols to be displayed for one of the subsets of display positions. 
     In an embodiment, the subsets are columns of display positions that correspond to respective ones of a plurality of reels such that modifying a game outcome corresponds to replacing a reel with a designated set of symbols. 
     In an embodiment, when symbols are selected for display, the game controller selects a stop position for each reel. 
     In an embodiment, the designated set of symbols is displayed under control of the game controller as a spinning reel consisting of the designated set of symbols. 
     In an embodiment, each of the designated symbols is a special symbol having an increased play characteristic relative to other symbols. 
     In an embodiment, the special symbol is a wild symbol. 
     In an embodiment, the game controller is arranged to make a third modification of generation of a game outcome for at least one subsequent game round in response to determining that a third condition is met, the modification comprising causing a third designated set of symbols to be displayed for one of the subsets of display positions. 
     In an embodiment, the game controller comprises a prize evaluator arranged to evaluate for each game round whether the generated game outcome includes one or more winning outcomes. 
     In an embodiment, evaluations are performed in a designated order of symbol sets, and modification occurs in the opposite order. 
     In an embodiment, winning outcomes are evaluated on a left to right basis and reels are replaced right to left. 
     In an embodiment, there are five sets of display positions. 
     In an embodiment, each set of display positions has three display positions. 
     In an embodiment, the gaming system comprises a random number generator employed in selecting the symbols. 
     In an embodiment, any modification is also applied to the current game round. 
     In an embodiment, the gaming system comprises a memory and processor arranged to execute program code stored in the memory to implement the game controller. 
     In an embodiment, the gaming system comprises a game play mechanism operable by a player at least to initiate a play of the game. 
     In a fourth aspect, the invention provides computer program code which when executed implements the above method. 
     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 comprising the above program code. 
     In a seventh aspect, the invention extends to transmitting the above program code. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
       An exemplary embodiment of the invention is described in relation to the following drawings, in which: 
         FIG. 1  is a block diagram of the core components of a gaming system. 
         FIG. 2  is a perspective view of a stand alone gaming machine; 
         FIG. 3  is a block diagram of the functional components of a gaming machine; 
         FIG. 4  is a schematic diagram of the functional components of a memory; 
         FIG. 5  is a schematic diagram of a network gaming system; 
         FIG. 6  is a further block diagram of a gaming system; 
         FIG. 7  is a flow chart of an embodiment; and 
         FIGS. 8A to 8E  are exemplary symbol displays of a first example. 
     
    
    
     DETAILED DESCRIPTION 
     Referring to the drawings, there is shown a gaming system having a game controller arranged to implement a game of the type where symbols are selected for display at a plurality of subsets of symbol positions, such as a spinning reel type game, wherein each reel corresponds to a subset of the symbol positions. If a first condition is met, a designated set of symbols is displayed in one of the subsets in a subsequent game round. In a spinning reel embodiment, this can be achieved by replacing all of the symbols of a reel with special symbols (e.g. wild symbols) for the subsequent game round. Symbols are selected for the other subsets in the normal manner. If a second condition is met a further designated set of symbols is displayed at a further one of the subsets in a further subsequent game round. Accordingly, in a spinning reel type embodiment, two or more reels may become wild. 
     General Construction of Gaming System 
     The gaming system can take a number of different forms. 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. 
     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 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, 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 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 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, 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 components are a player interface  50  and a game controller  60  as illustrated in  FIG. 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. 
     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 , a game play mechanism  56  that enables a player to input game play 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  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 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. 
     A gaming system in the form of a stand alone gaming machine  10  is illustrated in  FIG. 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 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 chute  24 A and a bill collector  24 B. 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 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 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 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 . 
     The display  14  shown in  FIG. 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 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. 
       FIG. 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  FIG. 2 . 
     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 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 including ensuring regulatory compliance and monitoring player credit, an input/output (I/O) interface  105  for 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 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. 
     In the example shown in  FIG. 3 , a player interface  120  includes peripheral devices that communicate with the game controller  101  and comprises 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 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. 
     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 data or commands from the central controller, server or database. 
       FIG. 4  shows a block diagram of the main components of an exemplary memory  103 . The memory  103  includes RAM  103 A, EPROM  103 B and a mass storage device  103 C. The RAM  103 A typically temporarily holds program files for execution by the processor  102  and related data. The EPROM  103 B may be a boot ROM device and/or may contain some system or game related code. The mass storage device  103 C 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  103 B or elsewhere. 
     It is also possible for the operative components of the gaming machine  100  to be distributed, for example input/output devices  106 ,  107 ,  108 ,  109 ,  110 ,  111  to be provided remotely from the game controller  101 . 
       FIG. 5  shows a gaming system  200  in accordance with an alternative embodiment. The gaming system  200  includes a 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  FIG. 5 , are connected to the network  201 . The gaming machines  202  provide a player operable interface and may be the same as the gaming machines  10 , 100  shown in  FIGS. 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  FIG. 5 , banks of one, three or more gaming machines are also envisaged. 
     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 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 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 management server  206  may manage storage of game programs and associated data for downloading or access by the gaming devices  202  in a database  206 A. Typically, if the 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. 
     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, 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 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 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 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, 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 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 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 game servers could be provided to run different games or a single game server may run a plurality of different games as required by the terminals. 
     Persons skilled in the art will also 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 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). 
     Further Detail of Gaming System 
     Referring to  FIG. 6 , it will be appreciated that the processor  62  implements a number of modules  621 - 625  based on computer program code stored in memory  64  of controller  60 . Persons skilled in the art will appreciate that some of these modules could be implemented differently, for example as dedicated hardware modules. 
     To play the gaming system, a player operates instruction input mechanism  56  to make an input or inputs (typically a wager) which will specify their win entitlement  645  for a game. The instruction input mechanism, thus providing a mechanism that enables game play. 
     Persons skilled in the art will appreciate that the nature of a win entitlement which the player can establish will vary from game to game and may or may not be dependent on player selections. In most spinning reel games, it is typical for the player&#39;s entitlement to be affected by the amount they wager and selections they make (i.e. the nature of the wager). For example, a player&#39;s win entitlement may be based on how many lines they will play in each game—i.e. a minimum of one line up to the maximum number of lines allowed by the game (noting that not all permutations of win lines may be available for selection. In many games, the player&#39;s win entitlement is not strictly limited to the lines they have selected, for example, “scatter” pays are awarded independently of a players selection of pay lines and are an inherent part of the win entitlement. 
     Persons, skilled in the art, will appreciate that in other embodiments, the player may obtain a win entitlement by selecting a number of reels to play. Such games are marketed under the trade name “Reel Power” by Aristocrat Leisure Industries Pty Ltd. The selection of the reel means that each symbol of the reel can be substituted for a symbol at one or more designated display positions. 
     In other embodiments a player win entitlement may be defined by purchasing access to particular pay tables—e.g. a first bet amount entitles the player to wins including cherries and a second amount entitles them to wins including plums. The win entitlement is not always purchased—e.g. a series of free games may be awarded. 
     Once the win entitlement has been established it is stored in memory  64  as win entitlement data  645  so that it can be used by the prize evaluator  623  to determine whether the player has achieved any winning outcomes to be paid from the prize table  646 . Game rules  644  specify how the players input is converted to a win entitlement, for example, by specifying the combinations of symbol positions which make up a win line that the player has selected. 
     In the embodiment illustrated in  FIG. 6 , it is envisaged that the game is implemented as a feature game with a number of bonus rounds and accordingly, a bonus round controller  624  employs a condition monitor  624 A to monitor for conditions specified by condition data  643  occurring in the game carried out by the game controller  60  in order to start the feature. When a feature game trigger condition occurs as monitored by the condition monitor  624 A, the bonus round controller  624  conducts a series of bonus game rounds. 
     During normal game rounds, the outcome generator  622  generates game outcomes by selecting symbols for display at a plurality of display positions on display  50 , the display positions are divided into a plurality of subsets of display positions and the selection of symbols for each subset of display positions is made from different ones of a plurality of symbol sets specified by the symbol data  641 . Outcomes and other aspects of game play are displayed on display  54  under controller of display controller  625  which may incorporate an appropriate driver for display  54 . 
     In an embodiment, when the feature game starts the generation of outcomes is modified for at least one subsequent game round by causing a designated set of symbols to be displayed for one of the subsets display positions. To this end, the outcome generator  622  includes a symbol selector  622 A which uses random number generator  621  to select symbols from symbol data  641  during normal game rounds and a designated symbol controller  622 B which controls the generation of subsequent outcomes such that the designated symbols specified by designated symbol data  642  are displayed in one of the subsets of displays positions. In such game rounds, the symbol selector  622 A will select symbols using random number generator  621  from the symbol data for the remaining subsets of display position. 
     In an alternative embodiment, the generation of outcomes is not modified in the first round of the feature game and it is not until a condition specified by condition data  643  is monitored as occurring by the condition monitor  624 A during a bonus game round that a modification is made to outcome generation such that the designated symbol controller  622 B is employed as described above. In one embodiment, the designated symbols are also replaced for the current game round such that the prize evaluation by the prize evaluator  623  on a modification of the selected symbols where symbols of one symbol set are replaced by the designated symbol controller  622 B. In other embodiments the designated symbols are not employed in prize evaluation until a subsequent game round. 
     The length of the series of game rounds may be controlled in a number of different manners, including by a specific number of game rounds being specified in the game rules  644  or by a value of prizes won, or if a specific prize is won, etc. In a specific embodiment, a second subset of symbols can be controlled such that only designated symbols are displayed in a subsequent game round in response to a second condition being met. In this embodiment, one option is for second subset to be one which neighbours the initial subset. Further subsets may also be controlled in response to further conditions being met. Subsets may also be selected in alternative ways, fro example, the player may be entitled to select the subset to be replaced, the subset that is selected may depend on the amount wagered, or the subset may be chosen randomly. 
     In one embodiment, the subsets are columns of display positions that correspond to respective ones of a plurality of reels in a spinning reel type game such that modifying a game outcome corresponds to replacing a reel with a designated set of symbols. In such embodiments, the symbol selector  622 A selects symbols by selecting stop positions for each of the plurality of reels. In such embodiments, the symbol data  641  specifies the symbol sequence for each reel such that selecting the stop position is determinative of the symbols which will appear on the display. Persons skilled in the art will appreciate that a weighting may be applied to particular stop positions or symbols in order to increase the chance of particular stop positions being selected by the random number generator  621 . 
     In one embodiment, the designated symbols may be displayed as a spinning reel consisting solely of the designated set of symbols. The designated symbols may be the same symbol for example, a special symbol which has an additional play characteristic relative to other symbols. Such symbols include, for example a wild symbol which has the additional play characteristic that is able to replace other symbols or a multiplier symbol which has the characteristic that it multiplies the value of symbol combinations. Other special symbols are known to persons skilled in the art. Alternatively, the designated symbol may be one to which high value awards are related. 
     In one embodiment, evaluation of whether a symbol combination is a winning outcome is performed in a designated order of symbol sets and the modifications occurs in the opposite order. This has particular application in a spinning reel embodiment. In such an embodiment if symbol combinations are evaluated left to right then it is possible for example to modify the right most reel first and then if the subsequent modification is required modify the next most right reel. Alternatively, in such an embodiment, as modifying a reel will have a greater benefit the closer it is to the left, the reel that is modified can depend on a factor related to the benefit intended to be provided to the player, for example, the left most reel might be modified if the player is playing max bet or if there are multiple trigger conditions and a less likely trigger occurs. 
     In one specific embodiment there are five sets of display positions (e.g. five reels) in each set of display positions has three display positions (e.g. three displayed symbols per reel). 
     The method  700  of the invention is summarised in  FIG. 7 . A feature trigger occurs  710 . The outcome generator then selects symbols  720 . It is then determined whether a condition is met  730  and if not, the method proceeds to evaluating the outcome  750 . If a condition is met symbols are replaced for a subset of symbols  740 . Then the game outcome is evaluated  750 . It is then determined whether to generate a further game outcome in which case the replaced symbols are held  765  on the display and symbols are only selected for non held positions. That is for example, by only spinning a subset of the reels in a spin reel embodiment. If a further game outcome is met, the feature ends  770 . Further aspects of the method will be apparent from the above description of the gaming system. 
     Persons skilled in the art will appreciate that other implementations are possible, for example if the replaced symbols are wild symbols, the game can be implemented on a stepper machine by providing three consecutive wild symbols on each reel for which the symbols can be replaced. The stopping positions of these reels are then controlled such that the wild symbols are displayed at the relevant position. 
     Example 1 
     Referring to the  FIGS. 8A to 8E  there is shown an example where once a feature game is triggered, the entire right most reel will become wild. That is all positions on the reel are treated as wild. This can be displayed in a number of manners either changing all symbols on the reels as turning symbols turning into wild symbols at both visible and non visible positions and subsequently spinning the reel or by simply holding that reel in place such that, in effect, the game controller  60  causes wild symbols to be continued to be displayed at the display positions while subsequent game rounds in the forms of further spins are played. 
     In this example, symbol combinations pay left to right and the trigger for turning a reel wild is the first time a wild symbol occurs on the right most reel during a triggered feature game. The feature itself can be triggered in accordance with any techniques known in the art including based on turnover, based on a signal from a system, based on a particular symbol combination etc. 
     In a five reel game, the addition of the wild reel greatly improves the odds of earning a five kind win in subsequent spins. The wild reel is designed to persist for a time, for example, for the duration of the feature game which may have a designated number of games, for example five games. While the fifth reel is wild, additional conditions such as a feature re-trigger or wild anywhere on the fourth reel turns the entire fourth reel wild. Thus the wild reels “creep” or “spread” from right to left increasing the chances of five of a kind type wins provided in the pay table. 
       FIGS. 8A to 8E  show an example where there are three pay lines  821 ,  822 ,  823  and five reels  811  to  815 . In the first spin of the feature, all symbols on the fifth reel turn  815  turn wild and only reels  1  to  4   811  to  814  are spun subsequently. As is shown in  FIG. 8A , the centre line  822  has a win for five queens and a prize is paid by the prize evaluator  623  for five queens. In the second feature spin again only reels  1  to  4 ,  811  to  814  spin. After this spin a prize is paid for five jacks on the top line  821  and three kings on bottom line  823 . Note that the wild in the bottom position on reel three has no persistent effect because reel four is not wild. 
     A third feature spin is shown in  FIG. 8C . While there are wilds on reel  1  and reel  4 , the effects are different and the wild symbol causes all symbols on the fourth reel  814  to be modified such that the game will change to show the symbols shown in  FIG. 8D  and pay for five aces on the bottom reel on the bottom line  823 . A further spin is conducted and it will be seen from  FIG. 8E  that the wild reel is held for the fourth reel  814  and five tens are paid for by the prize evaluator  623  in respect of the middle line  822 . 
     Example 2 
     In a further example, a game is triggered in accordance with one of the known trigger conditions such as the occurrence of a symbol combination the outcome of a feature game, the passage of time, a system, machine or operator event, a prize value being awarded, a special bet being placed or an event related to a player loyalty card. 
     The duration of the game is controlled by the bonus controller  624 , and the end can be in accordance with any of the known techniques in the art. Including the expiration of a fixed number of games, the expiration of a special criteria, the occurrence of a symbol or combination of symbols, time elapsing or a prize value being won. 
     In some embodiments there may be an extension to the period. The extension can include other reels of additional criteria. The additional criteria can be the same as the criteria which commenced the change or can be other criteria. In this example, once a player has entered the feature sequence, during the feature the number of symbols of a particular type, in this example “chilli” symbols which stop in any of the display positions are counted and a tally is kept. When the tally reaches a specified number, all symbols on the last reel change to become wild. In this example pays are evaluated left to right. These symbols remain wild until the feature sequence is completed. 
     The tally continues and if the tally reaches a second specified number (and hence a further condition is met) all symbols on the second last reel become wild. Again, these symbols remain wild until the feature sequence is completed. 
     The tally continues and if the tally reaches a third specified number, all symbols on the third last reel will become wild. These symbols remain wild until the feature sequence is completed. 
     It will be understood to persons skilled in the art of the invention that many modifications may be made without departing from the spirit and scope of the invention. In particular, that features of various embodiments described above can be combined to form further embodiments. 
     It is to be understood that, if any prior art publication is referred to herein, such reference does not constitute an admission that the publication forms a part of the common general knowledge in the art, in Australia or any other country. 
     In the claims which follow and in the preceding description of the invention, except where the context 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 features in various embodiments of the invention.