AU2009202162A1

AU2009202162A1 - Gaming machine with adjustable return to player

Info

Publication number: AU2009202162A1
Application number: AU2009202162A
Authority: AU
Inventors: Paul Bramble
Original assignee: Aristocrat Technologies Australia Pty Ltd
Current assignee: Aristocrat Technologies Australia Pty Ltd
Priority date: 2008-06-02
Filing date: 2009-06-01
Publication date: 2009-12-17
Also published as: US20090298573A1

Description

P/00/01i1 Regulation 3.2 AUSTRALIA Patents Act 1990 COMPLETE SPECIFICATION STANDARD PATENT Invention Title: Gaming machine with adjustable return to player The following statement is a full description of this invention, including the best method of performing it known to us: 2 Gaming machine with adjustable return to player Field of the invention The present invention generally relates to gaming machines and methods of gaming. Background of the invention 5 With the increase of gambling at gaming venues has come increased competition between gaming venues to obtain a larger share of the total gambling spend. Gaming venue operators have therefore continuously looked for new variations and types of games in order to attract both new and return customers to their venues. In response to this need, suppliers of gaming devices and systems have attempted to 10 provide the sought after variety, while still developing games that comply with the relevant regulations in the jurisdiction of the gaming venue operator. Suppliers of gaming devices therefore are faced with restrictions on the types of games and gaming machines that are allowable, both in terms of the prevailing regulations and in terms of providing a return on investment to the gaming venue operators. 15 In addition, suppliers need to control the cost of manufacturing gaming machines, including costs involved in the design of games provided by gaming machines. Any requirement to provide machines with different characteristics can lead to increased cost in design and/or manufacture. For example if different jurisdictions or different gaming venues within the same jurisdiction require the same themed game but with 20 different return to player values, then supplying a range of product to meet these requirements can lead to increased costs. Summary of the invention In one aspect the present invention provides a method for use with a gaming machine that is arranged to provide a game including displaying symbols on a display and 25 awarding an award if a winning outcome occurs, the gaming machine operating to have an overall statistical return, which is influenced by a pay characteristic, wherein the 3 method includes, prior to determining the outcome of a game play of the game, allocating to that game play one of a plurality of different said pay characteristics, wherein if a first said pay characteristic was permanently the allocated characteristic, the game would have a first statistical return less than the overall statistical return, and if 5 a second said pay characteristic was permanently the allocated characteristic, the game would have a second statistical return greater than the overall statistical return, and wherein the method includes allocating the plurality of different pay characteristics to game plays according to a weighted random selection process so as to result in the gaming machine having the overall statistical return. 10 One outcome of the game may be the award of a certain number of free game plays of the game and wherein the first pay characteristic is the award of a first number of free games on the occurrence of that outcome and the second pay characteristic is the award of a second number of free games on the occurrence of that outcome. The allocation may be made before commencement of the game play. 15 The allocation may be made after it has been determined that said outcome will occur. The first pay characteristic may be the random selection of symbols from a first symbol set and the second pay characteristic is the random selection of symbols from a second symbol set. The game is a spinning reel game and the first symbol set is a first reel and a second 20 symbol set is a second reel and the weighted random selection process includes selecting the first or the second reel for use in the game. The weighted selection process may select between only the first reel and the second reel. Alternatively, the weighted selection process may select between three or more alternative reels. 25 The game maybe a spinning reel game and the first symbol set is a first reel strip portion of a combined reel of the game and a second symbol set is a second reel strip portion of the combined reel, wherein the first and second reel strip portions consist of 4 alternate implementations of the game with different statistical returns, and wherein the number of first and second reel strip portions are provided in proportion to result in said overall statistical return so that the weighted random selection process includes selecting the stopping position of the combined reel. 5 The first pay characteristic and the second pay characteristic may be selected from the group comprising: alternative symbol sets in the game provided in proportion so as to result in the overall statistical return; alternative awards in the game provided in proportion so as to result in the overall statistical return; alternative trigger event probabilities provided in proportion so as to result in the overall statistical return; and 10 alternative award multipliers, provided in proportion so as to result in the overall statistical return. The first and second pay characteristics may be of the same type and differ only as to their magnitude. The first and second pay characteristics may operate only in a base game of the game. 15 The game may include a feature game. The first and second pay characteristics may operate only in a feature game of the game. The allocation for a game play may be independent of the allocation for any other game play. 20 In the weighted random selection process the probability of selecting the first pay characteristic may be calculated according to the formula: p1 = (S - R2)/(R1 - R2) and the probability of selecting the second pay characteristic may be calculated according to the formula: 5 p2 = (1 - p1), where: p1 = the probability of selecting the first pay characteristic set in the weighted random selection process; 5 p2 = the probability of selecting the second pay characteristic in the weighted random selection process; S = the overall statistical return to player value; R1 = the statistical return associated with the first pay characteristic; R2 = the statistical return associated with the second pay characteristic; and 10 R1 5S 5R2. In a second aspect the present invention provides a method for use with a gaming machine that is arranged to display symbols on a display and award an award if a winning outcome occurs, the gaming machine operating in accordance with an overall statistical return to player, the gaming machine provided with a plurality of symbol sets 15 including at least a first symbol set and a second symbol set, the first symbol set having a first associated return to player value and the second symbol set having a second associated return to player, wherein the first associated retum to player value is less than the overall statistical return to player, and the second associated return to player value is greater than the overall statistical return to player, wherein the method includes 20 selecting between the plurality of symbol sets for display on the display, wherein the selection is a weighted random selection process that results in the game having the overall statistical return to player. During each play of the gaming machine the gaming machine may randomly select symbols from the selected symbol set for display on the display. 25 The gaming machine may be a reel type gaming machine and the display includes a plurality of reel strip display positions, and wherein each symbol set includes symbols arranged into a plurality of reel strips, the plurality of reel strips corresponding respectively to the plurality of reel strip display positions.

6 The first symbol set and second symbol set may differ from each other only in respect of a single reel strip. The plurality of symbol sets may differ from each other by at least one characteristic selected from the group of a symbol type and a bonus associated with the set of 5 symbols. The weighted random selection process the probability of selecting the first symbol set may be calculated according to the formula: p1 = (S - R2)/(R1 - R2) and the probability of selecting the second symbol set may be calculated according to 10 the formula: p2 = (1 - p1), where: p1 = the probability of selecting the first symbol set in the weighted random selection process; 15 p2 = the probability of selecting the second symbol set in the weighted random selection process; S = the overall statistical return to player value; R1 = the first associated return to player value; R2 = the second associated return to player value; and 20 R1 5S R2. According to a further aspect, the invention broadly resides in instructions executable by a game controller to implement the method as described in the preceding paragraphs and to such instructions when stored in a storage medium readable by the game controller.

7 In a third aspect the present invention provides a gaming machine that provides a game based on a wager, the gaming machine comprising a user interface in communication with a game controller, the game controller adapted to implement the method as described above. 5 According to a further aspect, the invention broadly relates to a data signal carrying instructions and/or data executable to implement the method as described above. Further aspects of the present invention and further embodiments of the aspects described in the preceding paragraphs will become apparent from the following description, given by way of example and with reference to the accompanying drawings. 10 Brief description of the drawings Figure 1: shows diagrammatically, a view of a gaming console suitable for implementing the present invention. Figure 2: shows a block diagram of gaming machine suitable for implementing the present invention. 15 Figure 3: shows a block diagram of components of the memory of the gaming machine represented in Figure 2. Figure 4: shows diagrammatically, a network gaming system suitable for implementing the present invention. Figure 5: shows a depiction of a sample game screen for use with embodiments of 20 the present invention. Figure 6: shows a depiction of a sample game screen for use with embodiments of the present invention. Figure 7: shows reel strip depictions for the purposes of explaining embodiments of the present invention.

8 Figure 8: shows a flow diagram of a process performed in accordance with an embodiment of the present invention. Detailed description of the embodiments In Figure 1 of the accompanying drawings, one example of a gaming console that is 5 suitable to implement the present invention is generally referenced by arrow 114. The gaming console 114 includes two displays 106A, 106B on one or both of which is displayed representations of a game that can be played by a player and a bank of buttons 107A and/or a touch screen 107B to enable a player to play the game. The displays 106 may be video display units, such as a cathode ray tube screen device, a 10 liquid crystal display, plasma screen, any other suitable video display unit, or the visible portion of an electromechanical device. The display 106B may display artwork, including for example, pay tables and details of bonus awards and other information or images relating to the game. In alternative gaming consoles the display 106B may be omitted, optionally replaced by a static display. 15 A credit input including a coin input 110A and/or bill collector 11OB allows a player to provide credit for wagering and a coin output 111 is provided for cash payouts from the gaming console 114. A card and/or ticket reader 108 and a printer 109 may be provided to provide player tracking, cashless game play or other gaming and non-gaming related functions. 20 Figure 2 shows a block diagram of a gaming machine, generally referenced by arrow 100, suitable for implementing the present invention. The gaming machine 100 may include the gaming console 114 shown in Figure 1 and accordingly like reference numerals have been used to describe like components in Figures 1 and 2. The gaming machine 100 includes a game controller 101, which in the illustrated 25 example includes a computational device 102, which may be a microprocessor, microcontroller, programmable logic device or other suitable device. Instructions and data to control operation of the computational device 102 are stored in a memory 103, which is in data communication with, or forms part of, the computational device 102.

9 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 instructions to cause the game controller 101 to implement the present invention will be stored in the memory 103. The instructions and 5 data for controlling operation of the computational device 102 may be stored on a computer readable medium from which they are loaded into the gaming machine memory 103. The instructions and data may be conveyed to the gaming machine by means of a data signal in a transmission channel. Examples of such transmission channels include network connections, the Internet or an intranet and wireless 10 communication channels. The game controller 101 may include hardware credit meters 104 for the purposes of regulatory compliance and also include an input/output (1/O) interface 105 for communicating with the peripheral devices of the gaming machine 100. The input/output interface 105 and/or the peripheral devices may be intelligent devices with their own 15 memory for instructions and data. In the example shown in Figure 2, the peripheral devices that communicate with the controller are the displays 106, bank of buttons/touch screen 107, the card and/or ticket reader 108, the printer 109, a bill acceptor and/or coin input 110 and a coin output 111. Additional devices may be included as part of the gaming machine 100, or devices 20 omitted as required for the specific implementation. The bank of buttons 107A and/or touch screen 107B together with one or both of the displays 106 may provide a user interface 115 through which the gaming machine 100 and player communicate. If a card/ticket reader 108 is provided, this may also form part of the user interface 115. 25 In addition, the gaming machine 100 may include a communications interface, for example a network card 112. The network card 112, 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. The network card 112 may also enable communication with a central player account, 10 allowing cashless gaming. One or more of the peripheral devices, for example the card/ticket reader 108 may be able to communicate directly with the network card 112. The network card 112 and the 1/O interface 105 may be suitably implemented as a single machine communications interface. 5 The game controller 101 may also include a random number generator 113, which generates a series of random numbers that are used by the computational device 102 to determine the outcomes of games played on the gaming machine 100. The game controller 101 may have distributed hardware and software components that communicate with each other directly or through a network or other communication 10 channel. The game controller 101 may also be located in part or in its entirety remote from the user interface 115. Also, the computational device 102 may comprise a plurality of devices, which may be local or remote from each other. Instructions and data for controlling the operation of the user interface 115 may be conveyed to the user interface 115 by means of a data signal in a transmission channel. The user interface 15 115 may be a computational device, for example a personal computer, used by a person to play a game provided from a remote game controller 101. Figure 3 shows an exemplary block diagram of the main components of the memory 103. The RAM 103A typically temporarily holds instructions and data related to the execution of game programs and communication functions performed by the 20 computational controller 102. The EPROM 103B may be a boot ROM device and/or may contain system and game related code. The mass storage device 103C may be used to store game programs, the integrity of which may be verified and/or authenticated by the computational controller 102 using protected code from the EPROM 103B or elsewhere. 25 Figure 4 shows a gaming system 200 in the form of a network of devices. The gaming system 200 includes a network infrastructure 201, which for example may be in the form of an Ethernet network. Alternatively, a wireless network and/or direct communication channels, or a different type of network may be used to link the gaming machines to a server, each other and/or other devices. Gaming consoles 114, shown arranged in three l1 banks 203 of two gaming consoles 114 in Figure 4, are connected to the network infrastructure 201. The gaming consoles 114 may form part or all of a gaming machine 100. Single gaming consoles 114 and banks 203 containing three or more gaming devices 114 may also be connected to the network infrastructure 201, which may also 5 include bank controllers, hubs, routers, bridges to other networks and other devices (not shown). One or more displays 204 may also be connected to the network 201. The displays 204 may, for example, be associated with a bank 203 of gaming consoles 114. The displays 204 may be used to display representations associated with game play on the gaming 10 devices 114, and/or used to display other representations, for example promotional or informational material. Servers may also be connected to the network 201. For example, a game server 205 may generate game outcomes for games played on one or more of the gaming consoles 114, a database management server 206 may manage the storage of game 15 programs and associated data in a database 206A so that they are available for downloading to, or access by, game controllers 101, and a jackpot server 207 may control one or more jackpots for the gaming system 200. Further servers may be provided to assist in the administration of the gaming system 200, including for example a gaming floor management server 208, and a licensing 20 server 209 to monitor the use of licenses to particular games. An administrator terminal 210 is provided to allow an administrator to manage the network 201 and the devices connected to the network. The different servers depicted can be distinct physical servers or logically distinct server processes running on a single physical server. The gaming system 200 may communicate with other gaming systems, other local 25 networks, for example a corporate network and/or a wide area network such as the Internet through a firewall 211. The game controller 101 is programmed to provide a gambling game with a value for the return to player (RTP). The RTP is the overall statistical return to a player of the 12 machine. For example, if a game controller 101 is operating in accordance with a RTP of 90%, a player will (statistically) be awarded with 90 cents for each $1 wagered on the machine. It is often desirable to be able to alter the RTP of any given gaming machine. The RTP 5 may, for example, need to be changed to comply with various regulations (which may differ from location to location) or to comply with individual casino or gaming establishment requirements. The RTP of a game can be determined from the combination of the paytable for the game together with the specific set of symbols and the probability of winning 10 combinations of symbols occurring. The paytables may, for example, include data on the particular combinations of symbols from the symbol set which, when occurring as a game result, constitute a winning event as well as the award associated with that winning event. The paytable or game rules may also include information such as the circumstances under which bonus games, free games, jackpots, and/or any other pay 15 characteristics may be awarded, which typically also influence the RTP. In order to allow for the RTP of a gaming machine to be set to different levels, in one embodiment a gaming machine is provided with a plurality of different symbol sets, each with its own associated RTP, from which the game controller 101 can make random selections in order to provide a game. By making a weighted random selection between 20 symbol sets with appropriate RTP's (as discussed below) the game controller 101 can be configured to operate in accordance with a specific RTP as required. To describe how the game controller 101 uses the plurality of symbol sets to provide a specific RTP (S), an example of a gaming machine provided with two symbol sets will be discussed. The RTP associated with the first symbol set (i.e. the RTP if the first 25 symbol set is used during game play) is R1. The RTP associated with the second symbol set is R2. If the gaming machine was required to have a specific RTP equal to R1, the game controller 101 would make random symbol selections from the first symbol set for every 13 game play. Similarly, if the specific RTP of the gaming machine needed to be set at the RTP of R2, the game controller 101 would make random symbol selections from the second symbol set for each game play. A specific RTP (S) between R1 and R2 may be provided by the game controller 101 5 making a weighted random selection between the first and second symbol sets. The selected symbol set is then used in a game play of the game. It is noted again here that the RTP is a statistical RTP across a distribution of games rather than a single game. Mathematically, this can be expressed as follows: * S = the specific RTP required for the gaming machine 10 * R1 = the RTP of the game if the first symbol set is used * R2 = the RTP of the game if the second symbol set is used Provided R1 5S !R2, there exists a probability p such that: 0 p 1 pR1 + (1-p)R2 = S 15 Accordingly, p may be calculated according to the following: p=(R2-S) (R2-R1) In order to achieve the desired RTP value this formula may be implemented in a variety 20 of ways. For example, the game controller 101 may use the value of p and for any given game select either the first symbol set or the second symbol set, from which the random symbol selections are made during game play, in a weighted random selection process such that the probability of selecting from the first symbol set in the selection process is p, and the probability of selecting from the second symbol set is (1-p).

14 The value of p or a mathematically equivalent or similar value may be a parameter of the gaming machine able to be set to a different level using an appropriate interface to the gaming machine, with appropriate safeguards to prevent unauthorised modification. Alternatively, the value of p may be set during game design and 'hard-coded' into the 5 gaming machine. In the latter case a range of different gaming machine controllers may be manufactured whereas if the value of p is settable, then a generic machine may be produced, which is subsequently set up for a particular jurisdiction or venue by setting a value for p. General example 1 10 By way of example, the RTP associated with the first symbol set may be 80% (i.e. R1 = 80%) and the RTP of the second symbol set may be 100% (i.e. R2 = 100%). If the gaming machine was required to have a specific RTP of 90% (i.e. S = 90%), then, using the aforementioned calculations, p = 0.5. That is, when selecting whether the first of second symbol set should be used during a given play of the game the game 15 controller 101 undertakes a weighted random selection process which has a 50% chance of returning the first symbol set for game play and a 50% chance of returning the second symbol set for game play. Alternatively, if a specific RTP of 95% is required (i.e. S = 95%) p = 0.25 and the game controller 101 selects a symbol set via a weighted random selection process which has 20 a 25% chance of retuming the first symbol set for game play and a 75% chance (i.e. 1 p) of returning the second symbol set for game play. General example 2 By way of a second example, the RTP associated with the first symbol set may be 60% (R1 = 60%) and the RTP associated with the second symbol set may be 1000% (R2 = 25 1000%). If the gaming machine requires a specific RTP of 90% (S = 90%), then p = 91/94. In the weighted selection process, therefore, the chance of returning the first symbol set for 15 game play would be 91/94*100 (approximately 97%) and the chance of returning the second symbol set for game play would be (1-(91/94))*100 (approximately 3%). As will be appreciated, the RTP of the gaming machine can be set at any value that falls between (or is equal to) the RTP associated with the first symbol set and the RTP 5 associated with the second symbol set. Figure 5 provides a depiction of the above process as used in a sample game screen 500 for display on one of the gaming display 106. The game screen 500 includes a symbol display area 502 which provides a plurality of symbol display positions 504. The game screen also includes a display for a credit meter 516, a meter indicating the wager 10 placed by a player 518 and a display for a win meter 520 showing the amount, if any, won by a player. During game play the game controller 101 determined which of the symbol sets 522 or 524 is to be used for game play, and then populates the symbol display positions 504 with a random selection of symbols from the selected symbol set. 15 Where more than two sets of symbols are provided, the lowest RTP value achievable for the gaming machine will be the lowest RTP associated with a set of symbols, and the highest RTP achievable for the gaming machine will be the highest RTP associated with a set of symbols. In order to provide a specific RTP falling between the lowest and highest RTP the game controller 101 is configured to make a weighted random 20 selection of which symbol set to use for any given game play in a manner similar to that described above. The selection may be made from all of the available sets of symbols, or the game controller 101 may select from combinations of two or more symbol sets, but less than all available symbol sets, to achieve the specifically required RTP. In the latter case the symbol sets that can not be selected are never used for the particular 25 implementation of the gaming machine, but may be used for other implementations. For example, if three alternative symbol sets A, B, and C are provided having associated RTP's of R1, R2 and R3, a specific RTP may be obtained by a combination 16 of R1 and R2, a combination of R2 and R3, a combination of R1 and R3, or a combination of R1, R2 and R3. Spinning reel game example By way of further example, the present invention may be used in relation to a spinning 5 reel type game. In this type of game the symbol sets are provided in the form of a plurality of reel strips, each reel strip including a number of adjacent symbols. During game play each reel strip in the symbol set is "spun" by the game controller 101 and randomly stopped to display a subset of symbols on the display. Prizes are then awarded in accordance with a paytable. 10 In order to allow for the specific RTP required for the gaming machine to be changed, the gaming machine may be provided with two or more entirely different sets of reel strips (i.e. two or more different symbol sets), each set of reel strips resulting in a different RTP. As described above, when playing the game the game controller 101 can make a weighted random selection of which set of reel strips to play for any given 15 game, and the weightings used in that weighed random selection will determine the statistical RTP for the gaming machine. As an alternative to providing entirely different and distinct symbol sets, however, a specific RTP could be provided by providing different reel strips. For example, the game machine may be a reel type game in which 5 reels are "spun". Referring to figure 6, the 20 display area 502 may be conceptually broken into a number of reel strip display positions corresponding to columns 506 to 514. During game play the game controller 101 "spins" a reel in each reel strip display position 506 to 514, stopping the reels to populate the symbol display positions 504 with symbols. In such a game it would be possible to have 4 of the reel strips associated with four reel 25 strip display positions (e.g. 508 to 514) constant (i.e. not changed between game plays) and provide the required specific RTP for the gaming machine by a weighted random selection of a reel strip to use in only one of the reel strip positions 506. By way of 17 example, in figure 6 two reel strips are shown for selection, reel strip 602 and reel strip 604. For example, reel strip 602 could provide a gaming machine with a particular RTP (RI) when used in combination with the 4 reel strips populating reel strip display positions 5 508 to 514, and reel strip 604 could provide a gaming machine with a different RTP (R2) when used in combination with the same 4 reel strips. In this scenario, a specific required RTP for the game machine that falls between the RTP associated with reel strip A 602 and the RTP associated with reel strip B 604 can be provided via a weighted random selection of which reel strips 602 or 604 to use in a given game play. 10 The weighting of this random selection may be calculated according to the formula described above, with reel strip A in this example the first symbol set, and reel strip B the second symbol set. In one embodiment the determination of which reel strip to use is determined for each and every game play of the game. In another embodiment, the determination of which reel strip to use may be determined for a group of game plays, 15 for example the next ten game plays. In the latter case, the two reels strips 602 and 604 may be provided to appear the same so that the player can not determine which reel strip is being used. In the earlier case, the reel strips may be visually different. It would, of course, also be possible to change any number of reel strips (i.e. any number of symbol sets) in this particular example (e.g. holding three reel strips constant 20 and changing the remaining two reel strips) provided the RTP associated with each combination of reel strips is known (which, in turn, allows the correct weighting to be used in the weighted random selection process). For example, in one embodiment there may be two options for the symbol sets, one with a combination of a first two reels (which may be the same or different to each other) in reel strip display positions 506 25 and 508 and another with a combination of a second two reels in those positions. In another example there may be two different reels available for selection in the reel strip display position 506 and two different reels available for selection in reel strip display position 508 and the reel used for each display position 506, 508 may be determined independently of each other. This leads to four different possibilities for the 18 symbol sets and the RTP can be determined for each and the probability of selecting each set to obtain a required specific RTP for the entire game. In addition, there may be three or more different options for symbols for a reel strip display position. Some efficiency however may be obtained if only two symbol sets are provided. In 5 addition, some efficiency and/or consistency between implementations may be obtained if only a part of the symbols sets are changed, for example one reel in a set of 3 reels or one deck of cards in a game that uses five or six decks of cards. The game may be designed so that the visual difference between the two alternative games that result from this process is small. For example, the reels may be shortened 10 in comparison to the usual 20 to 25 symbols so as to magnify the effect of swapping one symbol on one reel with another symbol on the alternative reel to that reel. For example a WILD symbol (W) may be changed with a SCATTER symbol (C). The reel strip may for example be between 7 and 15 symbols long. The alternative reels may have the same length or may have different lengths. 15 Combined reel strips As a further variation to the above reel type game example, instead of performing a weighted selection process to determine whether reel strip A or reel strip B should be used in any given game in order to provide a specific RTP, a single reel strip comprised of instances of reel strips A and B could be created and used for every game play. 20 The ratio that reel strips A and B need to be combined together in so as to provide the specific RTP required by the gaming machine is given by the formula for calculating p as described above: p = (R2 - S) (R2 - R1) 25 where: S = the specific RTP value required for the gaming machine 19 R1 = the RTP provided by the gaming machine if reel strip A is used R2 = the RTP provided by the gaming machine if reel strip B is used If p is expressed as a fraction in the form x/y (in its simplest form), the RTP value required for the gaming machine can by provided by always using a reel strip that is a 5 combination of x instances of reel strip A linked to (y- x) instances of reel strip B. By way of example, figure 7 provides a representation of reel strip 602 and representation of reel strip 604 (of course in practise it is likely that both reel strips A and B would be comprised of larger numbers of symbols). The end symbols of each reel strip are "joined" to another reel strip create a loop. 10 If the gaming machine requires a specific RTP of 90% (S = 90%) and the RTP associated with reel strip 602 is 80% (i.e. R1 = 80%), and the RTP associated with reel strip 604 is 100% (i.e. R2 = 100%) the above calculations show that p = %/ (0.5). In this case, therefore, rather than making a weighted random selection process between reel strip 602 and reel strip 604 to determine which reel strip should be used for a play of the 15 game (the weighted random selection process having a 50% probability of returning reel strip A and 50% probability of returning reel strip B), a single reel 614 that is a combination of one instance of reel strip A 602 and one instance of reel strip B 604 can be created and used for each game play. As can be seen, in the combined reel strip 614 the last symbol 608 of reel strip A 602 is adjacent the first symbol 610 of reel strip B 20 604. Alternatively, if the gaming machine requires a specific RTP of 95% (S = 95%) the above calculations show that p = % (0.25). Therefore, a specific RTP of 95% can be provided by playing the game with a combined reel strip 616 that is comprised of 1 instance of reel strip A 602 and 3 instances of reel strip B 604. 25 As will be appreciated, randomly spinning a combined reel strip as created above during game play is substantially equivalent to swapping between reel strips A and B in the ratios required to achieve the specific RTP required for the gaming machine. As will also be appreciated where "virtual" reel strips are to be used by the game controller only 20 a single copy of each reel strip need actually be stored, with the combined reel strips generated as required. To obtain a higher granularity in the possible specific RTP values, a higher number of reel strips may be used. In one embodiment the game is determined as if all reel strips 5 of the same type are joined together in a group. For example when the reel spins, it may spin through 10 instances of reel 602 and then 6 instances of reel strip 604 before returning to the 10 reels 602. When combining multiple reel strips into a single reel strip care should be taken to ensure that any transitional sections of the combined reel strip (i.e. a section of the reel 10 strip where a particular instance of a reel strip finishes and an instance of a new reel strip, or a new instance of the same reel strip, begins) do not significantly alter the RTP of the gaming machine from the specific RTP required. It is noted that the reel strips depicted in figure 7 are for general illustrative purposes only, and the specific combination of symbols depicted on these reel strips may not be appropriate depending 15 on gaming machine requirements of specific jurisdictions. Other variables As a further embodiment of the invention it would be possible to provide a gaming machine with a single set of symbols and with two or more paytables relating to those symbols. In the same manner as described above, if one of the paytables when used 20 with the set of symbols provides a RTP R1, and a second paytable when used with the set of symbols provides a RTP R2, then the gaming machine may be configured to provide a specific RTP S, where R1 < S < R2 by making a weighted random selection of which paytable should be used for any given game. Still other variables may be used to achieve different return to players, allowing 25 weighted selection between the resulting plurality of games that are possible. For example the RTP of a retriggerable game where the base and feature have the same RTP may be defined as: 21 RTP = B + Bmnt 1-nt Where B is the return provided by a base game of the game, t is the probability of a feature game occurring, n is a number of free games provided in the feature game and m is the multiplier of the prizes that applies for the feature game. 5 For this game, any of the variables B, m, n, or t may be varied to obtain a required RTP. B may be varied by changing the symbol sets as described herein above. m or n may be randomly selected between two values (or more) according to a weighted random selection process to result in the required RTP. If t is a symbol combination then this may be varied by changing the symbol sets. If the trigger event for the feature game is 10 determined independently of the symbols then that determination may be switched between two determination methods with different probabilities. For example in one game the trigger event for the feature game may be the selection of the number 1 in the range 1 to 100 and in another game may be the selection of any of 1 to 20 in the range 1 to 100. 15 As will be appreciated from the preceding discussion the characteristic that is varied may be solely within the base game or solely within a feature game. It would also be possible to vary more than one characteristic, with the consequent increased complexity in determining the overall RTP and appropriate weighting in the selection process. Figure 8 shows a process flow diagram of processes performed in accordance with an 20 embodiment of the present invention. In step 1, the RTP for the gaming machine is set. This may be set, for example, in accordance with the geographical location in which the game is to be used and the regulatory requirements of that location. If a suitable game controller 101 is used, the RTP of a gaming machine may be changed at any time either by direct interaction with 25 the gaming machine through the user interface or via instructions sent to the gaming machine over a network connection. As will be appreciated, however, sufficient security should be implemented to prevent unauthorised tampering of the RTP. Alternatively a 22 game may be manufactured with the RTP permanently set as described herein and shipped with that fixed RTP. In step 2 the weighting required to be used for the weighted random selection process in order to provide the gaming machine with the required RTP is calculated and stored 5 on the gaming machine. The weighting is calculated according to the formulae discussed above. The weighting may be calculated by the gaming machine itself and stored as a variable, or may be calculated by a manufacturer of the gaming machine and stored as a constant. Steps 1 and 2 relate to the manufacture and/or setting up of a gaming machine. Steps 3 10 to 7 apply to play of the gaming machine. In step 3 the game controller 101 monitors the bill acceptor and/or coin input 110 and/or information received by the card/ticket reader 108 or network card 112 for a deposit of credit and in response causes the hardware meters 104 to increment according to the denomination of the game. The game controller 101 then monitors the user interface 15 107 for the input of a wager. In step 4, and provided a user has sufficient credits, the user initiates a game. In step 5 the game controller 101 determines the symbol set that will be used for the game according to the weighted selection process described herein (assuming the embodiment where there are a plurality of alternative symbol sets). 20 In step 6 the game controller 101 makes a random selection of symbols from the symbol set selected in step 5 and displays the results. In step 7 the game controller 101 determines whether any award is payable and, if so, awards the award to the player. As will be appreciated, if the symbol sets selected in the weighted selection process are 25 symbol sets used in the base game, the determination of which symbol set to use for any given game play made in step 5 may be made at any time prior to making the symbol selection of step 6. If the alternative symbols sets or other variable that affects 23 RTP is for a feature game, then the process may be modified so that step 5 is completed only when required i.e. only when a feature game is played. While the foregoing description has been provided by way of example of the preferred embodiments of the present invention as presently contemplated, which utilise gaming 5 machines of the type found in casinos, those skilled in the relevant arts will appreciate that the present invention also may have application to internet gaming and/or have application to gaming over a telecommunications network, where handsets are used to display game outcomes and receive player inputs. Where in the foregoing description reference has been made to integers having known 10 equivalents, then those equivalents are hereby incorporated herein as if individually set forth. Those skilled in the relevant arts will appreciate that modifications and additions to the embodiments of the present invention may be made without departing from the scope of the present invention. 15 It will be understood that the invention disclosed and defined in this specification extends to all alternative combinations of two or more of the individual features mentioned or evident from the text or drawings. All of these different combinations constitute various alternative aspects of the invention. 20

Claims

1. A method for use with a gaming machine that is arranged to provide a game including displaying symbols on a display and awarding an award if a winning outcome occurs, the gaming machine operating to have an overall statistical return, which is 5 influenced by a pay characteristic, wherein the method includes, prior to determining the outcome of a game play of the game, allocating to that game play one of a plurality of different said pay characteristics, wherein if a first said pay characteristic was permanently the allocated characteristic, the game would have a first statistical return less than the overall 10 statistical return, and if a second said pay characteristic was permanently the allocated characteristic, the game would have a second statistical return greater than the overall statistical return, and wherein the method includes allocating the plurality of different pay characteristics to game plays according to a weighted random selection process so as 15 to result in the gaming machine having the overall statistical return.

2. The method of claim 1, wherein one outcome of the game is the award of a certain number of free game plays of the game and wherein the first pay characteristic is the award of a first number of free games on the occurrence of that outcome and the second pay characteristic is the award of a second number of free games on the 20 occurrence of that outcome.

3. The method of claim 2, wherein the allocation is made before commencement of the game play.

4. The method of claim 2, wherein the allocation is made after it has been determined that said outcome will occur. 25

5. The method of claim 1, wherein the first pay characteristic is the random selection of symbols from a first symbol set and the second pay characteristic is the random selection of symbols from a second symbol set. 25

6. The method of claim 5, wherein the game is a spinning reel game and the first symbol set is a first reel and a second symbol set is a second reel and the weighted random selection process includes selecting the first or the second reel for use in the game. 5

7. The method of claim 6, wherein the weighted selection process selects between only the first reel and the second reel.

8. The method of claim 6, wherein weighted selection process selects between three or more alternative reels.

9. The method of claim 5, wherein the game is a spinning reel game and the first 10 symbol set is a first reel strip portion of a combined reel of the game and a second symbol set is a second reel strip portion of the combined reel, wherein the first and second reel strip portions consist of alternate implementations of the game with different statistical returns, and wherein the number of first and second reel strip portions are provided in proportion to result in said overall statistical return so that the weighted 15 random selection process includes selecting the stopping position of the combined reel.

10. The method of claim 1, wherein the first pay characteristic and the second pay characteristic are selected from the group comprising: alternative symbol sets in the game provided in proportion so as to result in the overall statistical return; 20 alternative awards in the game provided in proportion so as to result in the overall statistical return; alternative trigger event probabilities provided in proportion so as to result in the overall statistical return; and alternative award multipliers, provided in proportion so as to result in the overall 25 statistical return,

11. The method of claim 10, wherein the first and second pay characteristics are of the same type and differ only as to their magnitude. 26

12. The method of claim 10, wherein the first and second pay characteristics operate only in a base game of the game.

13. The method of claim 12, wherein the game includes a feature game.

14. The method of claim 10, wherein the first and second pay characteristics operate 5 only in a feature game of the game.

15. The method of any one of claims 1 to 14, wherein the allocation for a game play is independent of the allocation for any other game play.

16. A method for use with a gaming machine that is arranged to display symbols on a display and award an award if a winning outcome occurs, the gaming machine 10 operating in accordance with an overall statistical return to player, the gaming machine provided with a plurality of symbol sets including at least a first symbol set and a second symbol set, the first symbol set having a first associated return to player value and the second symbol set having a second associated return to player, wherein the first associated return to player value is less than the overall statistical return to player, and 15 the second associated return to player value is greater than the overall statistical return to player, wherein the method includes selecting between the plurality of symbol sets for display on the display, wherein the selection is a weighted random selection process that results in the game having the overall statistical return to player. 20

17. The method according to claim 16, wherein during each play of the gaming machine the gaming machine randomly select symbols from the selected symbol set for display on the display.

18. The method according to either claim 16 or claim 17, wherein the gaming machine is a reel type gaming machine and the display includes a plurality of reel strip 25 display positions, and wherein each symbol set includes symbols arranged into a plurality of reel strips, the plurality of reel strips corresponding respectively to the plurality of reel strip display positions. 27

19. The method according to claim 18, wherein the first symbol set and second symbol set differ from each other only in respect of a single reel strip.

20. The method according to any one of claims 16 to 19, wherein the plurality of symbol sets differ from each other by at least one characteristic selected from the group 5 of a symbol type and a bonus associated with the set of symbols.

21. The method of any one of claims 1 to 15, wherein in the weighted random selection process the probability of selecting the first pay characteristic is calculated according to the formula: p1 =(S - R2) / (R1- R2) 10 and the probability of selecting the second pay characteristic is calculated according to the formula: p2 = (1 - p1), where: p1 = the probability of selecting the first pay characteristic set in the weighted random selection process; 15 p2 = the probability of selecting the second pay characteristic in the weighted random selection process; S = the overall statistical return to player value; R1 = the statistical return associated with the first pay characteristic; R2 = the statistical return associated with the second pay characteristic; and 20 RI :S R2.

22. The method of any one of claims 16 to 20, wherein in the weighted random selection process the probability of selecting the first symbol set is calculated according to the formula: p1 = (S - R2)/(R1 - R2) 25 and the probability of selecting the second symbol set is calculated according to the formula: 28 p2 = (1 - p1), where: p1 = the probability of selecting the first symbol set in the weighted random selection process; p2 = the probability of selecting the second symbol set in the weighted random selection 5 process; S = the overall statistical return to player value; RI = the first associated return to player value; R2 = the second associated return to player value; and R1 S 5R2. 10

23. A gaming machine that provides a game based on a wager, the gaming machine comprising a user interface in communication with a game controller, the game controller adapted to implement the method of any one of claims 1 to 22.

24. A computer program comprising machine-readable program code for controlling the operation of a data processing apparatus on which the program code executes to 15 perform the method of any one of claims 1 to 22.

25. A data signal carrying instructions and/or data executable to implement the method as described in any one of claims 1 to 21.