AU2007216640B2 - Gaming machine, system and method with progressive game feature - Google Patents

Description

P/00/OI I Regulation 3.2 AUSTRALIA Patents Act 1990 COMPLETE SPECIFICATION STANDARD PATENT Invention Title: Gaming machine, system and method with progressive game feature The following statement is a full description of this invention, including the best method of performing it known to us: 2 Gaming machine, system and method with a bonus feature Field of the Invention The present invention generally relates to gaming apparatus and methods of gaming. A particular embodiment of the present invention relates to gaming apparatus and 5 methods of gaming that offer a bonus feature. Another particular embodiment of the present invention relates to a gaming apparatus and method of gaming that offer a progressive prize. Background of the Invention With the increase of gambling at gaming venues has come increased competition 0 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 provide the sought after variety, while still developing games that comply with the 5 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 apparatus that are allowable, both in terms of the prevailing regulations and in terms of providing a return on investment to the gaming venue operators. In addition, it is important that a player be able to understand the operation of a game 20 quickly so that the player can start to quickly play the game and therefore extract maximum entertainment from the game. Progressive jackpots may be offered on gaming machines. A progressive controller may be programmed to accumulate a percentage of the turnover bet on the machine, that percentage being accumulated in a progressive pool. On the occurrence of a 25 predetermined event, the amount of money in the pool may be awarded to a player.

3 Recently progressive jackpot gaming systems have been implemented which operate across a group of linked gaming machines, accumulating a percentage of turnover bet on all of the linked machines into one or more progressive pools. Again the contents of a particular progressive pool may be awarded to a player when certain trigger 5 conditions are met. While the modified player progressive systems have increased player interest, the lack of actual or perceived player involvement in the increment of either standalone or linked progressive systems can mean that players may easily tire of playing these systems. One way of increasing player interest in gaming is to increase the variability of the 0 bonus awards. Typically, this is done by providing a base game having a bonus feature which is triggered on a reasonably regular basis. The bonus feature, when triggered, typically provides a feature game which itself has a range of bonus prizes, ranging from a small bonus prize which occurs most frequently, to a major or large jackpot prize, which occurs relatively rarely. Clearly, in order to keep the return to player percentage 5 within preset parameters, it is necessary that the major or large jackpot prize only occurs on infrequent occasions. The problem with this system is that players who do trigger the bonus feature usually win only the minor bonus prize, so that the triggering of the bonus feature is coupled with the somewhat negative expectation that the feature game will only result in a 20 modest reward. It is desirable to provide a gaming system which will increase the sense of anticipation for players on achieving a bonus feature. It may also be desirable to provide such a gaming system that increases the sense of anticipation for players on achieving a bonus but without altering the return to player percentage of the machine or system on which the bonus feature or bonus feature and feature game is being played. 25 Any reference in this specification to the prior art does not constitute an admission that such prior art was well known or forms part of the common general knowledge in any jurisdiction.

4 Summary of the invention According to a first aspect of the present invention, there is provided a gaming machine having a display and a user interface in communication with a game controller, which cooperate to provide a game in which a plurality of symbols from a symbol set are 5 displayed on the display to represent at least one game outcome that is evaluated for a winning combination and in which an award is awarded if a winning combination results, wherein a said winning combination is a bonus feature, the occurrence of which results in the game controller controlling game play of the game to provide at least a chance to win a bonus prize from a set of one or more bonus prizes, the game controller further 10 controlling the gaming machine to evaluate any bonus prizes awarded in the bonus feature to determine whether an eligibility criterion for a special prize has been met and in response to determining that the eligibility criterion has been met, additionally award the special prize, wherein the special prize is different from the awarded bonus prize(s) and has a value which is, at least in part, determined using a random selection process. 15 In one embodiment, the gaming machine does not display on the display symbols to represent the random selection process. In one embodiment, the gaming machine includes a pay schedule that advertises each of the one or more bonus prizes but does not advertise the at least one special prize. In one embodiment, the special prize is only awardable when a said bonus prize is won. 20 In one embodiment, there are at least two said bonus prizes that are winnable following occurrence of said bonus feature. In this embodiment, the plurality of different bonus prizes may include a plurality of progressive prizes that are formed so as have different values from each other. Instead, the plurality of different bonus prizes may include a plurality of fixed value prizes of different values. Also, the game controller may select 25 each of the plurality of different bonus prizes with different average expected frequencies. The bonus feature may always result in the award of a positive value bonus prize. The special prize may be awardable when at least one, but not all of the bonus prizes are won and also the special prize may be awardable when a first said bonus prize is won and not awardable when a second said bonus prize is won, the 5 second said bonus prize having a higher value than the first said bonus prize. The special prize may be awardable only when the bonus prize of lowest value is won. In one embodiment, the special prize is awarded in addition to the bonus prize and the gaming machine displays the combined special prize and bonus prize as a single prize 5 and does not display separate indications of each prize. In one embodiment, the award of the special prize is dependant on the player placing an additional bet. In one embodiment, there are a plurality of distinct bonus features representing different winning outcomes and wherein each bonus feature resulting in at least a chance to win 10 a bonus prize from a different set of one or more bonus prizes. In this embodiment the plurality of bonus features each result in a chance to win one of a plurality of different bonus prizes. In one embodiment, on occurrence of a bonus feature, the game controller commences play of a feature game in which representations of the feature game are displayed on 15 the display that indicate to the player the bonus prize that is to be awarded. According to another aspect of the present invention, there is provided a gaming system including a plurality of gaming machines as described in the preceding paragraphs, wherein each of the plurality of gaming machines are eligible to win the same said one or more bonus prizes when a said bonus feature occurs on that gaming machine. 20 In one embodiment, at least one of the one or more bonus prizes is a progressive prize to which each of the plurality of gaming machine contribute. According to another aspect of the present invention, there is provided a method of providing awards on a gaming machine that provides a wagering game in which a plurality of symbols from a symbol set are displayed on a display to represent play of 25 the wagering game, the method including providing as one possible outcome of the game a bonus feature; when the bonus feature occurs, providing at least a chance to win a bonus prize from a set of one or more bonus prizes; and when the bonus feature 6 occurs, evaluating any bonus prizes awarded in the bonus feature to determine whether an eligibility criterion for a special prize has been met and in response to determining that the eligibility criterion has been met, additionally awarding the special prize, wherein the special prize is different from the awarded bonus prize(s) and has a value 5 which is, at least in part, determined utilising a. In one embodiment, the random selection process determines whether or not the special prize is awarded. In one embodiment, the set of one or more bonus prizes includes a plurality of different bonus prizes and the process of providing a chance to win a bonus prize includes 10 selecting which one of a plurality of bonus prizes is to be won, the selection being controlled so that a bonus prize is always won when the bonus feature occurs, the method further including advertising in a pay schedule for the game the plurality of bonus prizes but not the special prize and performing the random selection process without displaying to a player symbols representing the result of the random selection 15 process and wherein the random selection process includes a selection of the value of the special prize so that the special prize awarded is a randomly variable prize. In one embodiment, the method further includes awarding a single prize as a combination of a said bonus prize and the special prize and displaying representations of the award of the special prize as if the combination of a said bonus prize and the 20 special prize was a single prize resulting from occurrence of the bonus feature. In one embodiment, the method further includes awarding the special prize instead of a said bonus prize and displaying representations of the award of the special prize as if the special prize was a single prize resulting from occurrence of the bonus feature.

7 In one embodiment, the method further includes awarding the special prize instead of a said bonus prize and displaying representations of the award of the special prize as if the special prize was a single prize resulting from occurrence of the bonus feature. In one embodiment, the method further includes displaying a feature game between 5 occurrence of the bonus feature and the award of the special prize, the feature game including representations that indicate a said bonus prize that is to be awarded if a special prize is not awarded. Further aspects of the present invention and further embodiments of the aspects described in the preceding paragraphs will become apparent from the following 0 description, given by way of example and with reference to the accompanying drawings. Brief description of the drawings Figure 1: shows diagrammatically, a view of a gaming machine suitable for implementing the present invention. Figure 2: shows a block diagram of gaming apparatus suitable for implementing the 5 present invention. Figure 3: shows a block diagram of components of the memory of the gaming apparatus represented in Figure 2. Figure 4: shows diagrammatically, a network gaming system suitable for implementing the present invention. 20 Figure 5: shows a flowchart of a game process in accordance with an embodiment of the present invention. Detailed description In Figure 1 of the accompanying drawings, one example of a gaming machine suitable for implementing the present invention is generally referenced by arrow 10.

8 The gaming machine 10 includes a console 12 having a display 14 on which is displayed representations of a game 16 (bounding box only shown in Figure 1), 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 play the game 16. The mid-trim 20 also houses a 5 credit input mechanism 24 including a coin input chute 24A and a bill collector 24B. 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 the front panel 29 of the console 12. A coin tray 30 is mounted beneath the console 12 for cash payouts from the gaming machine 10. 0 The display 14 shown in Figure 1 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 in a more preferred form of gaming machine 10 to implement the present invention includes a display, for example a video display 5 unit, which may be of the same type as the display 14, or a different type of display. Figure 2 shows a block diagram of a gaming apparatus, generally referenced by arrow 100, suitable for implementing the present invention. The gaming apparatus 100 may, for example, operate as a standalone gaming machine of the type shown in Figure 1. However, the gaming apparatus 100 may alternatively operate as a networked gaming 20 machine, communicating with other network devices, such as one or more servers or other gaming machines. The gaming apparatus 100 may also have distributed hardware and software components that communicate with each other directly or through a network. Accordingly, different reference numerals have been used in Figure 2 from Figure 1 for components that may be equivalent. 25 The gaming apparatus 100 includes a game controller 101, which in the illustrated 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 a part of the computational device 102. 30 Typically, the gaming apparatus 100 will include both volatile and non-volatile memory 9 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 gaming apparatus may include hardware meters 104 for the purposes of regulatory 5 compliance and also include an input/output (1/O) interface 105 for communicating with the peripheral devices of the gaming apparatus 100. The input/output interface 105 and/or the peripheral devices may be intelligent devices with their own memory for instructions and data. In the example shown in Figure 2, the peripheral devices that communicate with the 0 controller are one or more displays 106, user input devices 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. One or more of the displays 106 may include a touch screen 106A, forming part of the user input devices 107. Additional devices may be included as part of the gaming machine 100, or devices omitted as required for the specific 5 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 a the central controller, server or 20 database. 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 game controller 101 may also include a random number generator 113, which generates a series of random numbers that determine the outcome of a series of random game events played as part of a game on the gaming apparatus 100. As 25 explained in more detail in relation to Figure 4, the computational device 102 may include two or more controllers or processors, which may be local or remote from each other and the displays 106.

10 Figure 3 shows an exemplary block diagram of the main components of the memory 103. The RAM 103A typically temporarily holds program files for execution by the computational controller 102 and related data. The EPROM 103B may hold be a boot ROM device and/or may contain some system or game related code. The mass storage 5 device 103C is typically 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. Figure 4 shows a gaming system 200. The gaming system 200 includes a network 201, which for example may be an Ethernet network. Gaming devices 202, shown arranged 0 in three banks 203 of two gaming devices 202 in Figure 4, are connected to the network 201. The gaming devices 202 may be gaming machines 10, as shown in Figure 1 or form part or all of another gaming apparatus 100. Single gaming devices 202 and banks 203 containing three or more gaming devices 202 may also be connected to the network 201. 5 One or more system displays 204 may also be connected to the network 201. The system displays 204 may, for example, be associated with a bank 203 of gaming devices. The system displays 204 may be used to display representations associated with game play on the gaming devices 202, and/or used to display other representations, for example promotional or informational material. The bonus prizes 20 referred to later herein, which may be in the form of fixed or progressive prizes may be displayed on a system display 204. Servers may also be connected to the network 201. For example, a game server 205 may generate game outcomes for games played on the gaming devices 202, a database management server 206 may manage the storage of game programs and 25 associated data for downloading or access by the gaming devices 202 in a database 206A, and a jackpot server 207 may control one or more jackpots associated with the gaming devices 202. 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 11 server 209 to monitor the use of licenses 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 5 networks, for example a corporate network and/or a wide area network such as the Internet through a firewall 211. Figure 5 shows a process flow diagram 500 of a process performed in accordance with an embodiment of the present invention. The process may be performed by the network gaming system 200, in which the gaming devices 202 may each include part or all of a 0 gaming apparatus 100 and the following description assumes this implementation. However, those skilled in the relevant arts will appreciate that the process will also be able to be implemented by other gaming systems. The present invention provides a form of randomly awarded special prize to a player in addition to prizes that the player would expect to receive during normal play. As 5 described in more detail in the following paragraphs, the special prize may be awarded together with a bonus prize that is the result of occurrence of a bonus feature occurring during normal play or is the result of play of a feature game that is played following occurrence of a bonus feature. Also, a single bonus feature may result in one of a plurality of different bonus prizes. 20 The special prizes may be awarded only after a feature game has been triggered during play of the base game of a game. That is, special prizes will not be awarded during normal play of the base game, but once a bonus feature has occurred during normal play of the base game a feature game occurs, and eligibility for a special prize will then exist in addition to the player being eligible to win one or more bonus prizes dependent 25 on the outcome of the feature game. The one or more bonus prizes may be one or more progressive prizes, the progressive prizes starting at and/or incrementing at different levels if there is more than one. The one or more bonus prizes may be one or more fixed prizes, the fixed prizes having differing values. The description given with 12 reference to Figure 5 primarily refers in more detail to the processes involved in implementing a game having a base game and a feature game. In one embodiment there is a plurality of bonus prizes associated with the bonus feature. In this embodiment the bonus prize that is awarded is determined by the game 5 controller 101 according to a random selection process. The random selection process may be weighted so that smaller value bonus prizes statistically occur more often than the higher value bonus prizes. Although the description herein uses the example of a spinning reel game, the embodiments described herein will have application to other game formats, including by 0 way of non-limiting example card games, dice games and keno games. After a bet has been placed at step 501, a base game, which may for example be a spinning reel game is played (step 502). During the base game a bonus feature occurs according to random criteria (determined in step 504). For example, the bonus feature may be the alignment of say, three symbols alongside each other on a payline of the 5 gaming machine, or the occurrence anywhere on the screen of say, three special or wild symbols. Various forms of such events are known in the art and need not be described herein in any greater detail. An alternative arrangement is for the bonus feature to be triggered completely independently of the base game, for example based on turnover of the base game as 20 described in Australian patent no. 754689, the contents of which are hereby incorporated by reference. In this case there may be only a single prize pool while alternatively where multiple prize pools are provided, the prize pool that is played for may be selected randomly. Once the bonus feature has occurred or been triggered, the gaming device 202 displays 25 the feature game (step 506). This may be under the control of the same computational device 102 that controlled display of the base game. In an alternative embodiment, the game controller 101 may have a specific component that operates the feature game, which may be physically separate from a component that controls play of the base 13 game, or which may be a separate process provided using the same physical component. This alternative embodiment may have particular application to a plurality of linked gaming machines. Whichever form of bonus feature is triggered, and the manner of that triggering, a 5 feature game will be played, as indicated at step 508. In due course an outcome of the feature game will occur, as indicated at step 510. The outcome of the feature game will determine whether a bonus prize is awarded. In one embodiment there are a plurality of different bonus prizes that can be won from the feature game, the game controller determining which one, if any, of the bonus prizes is awarded according to random 0 criteria, which may be weighted towards the lesser value bonus prizes. In one version of this embodiment, one of the bonus prizes is always awarded from the feature game so that there are only winning outcomes of the feature game. At this point, rather than simply reverting back to the base game, the game controller assesses whether the player is eligible for a special or random prize, as indicated at 5 step 512. If the game controller 101 determines that the player is not eligible for a prize, the system reverts to the base game, as indicated at steps 518 and 501. However, if the game controller 101 determines that the player is eligible for a special prize then the value of that special prize will be determined, as indicated at step 514, and the player 20 will then be paid that special prize out of a progressive prize pool or other prize funds source. Thereafter the system will revert to base game play, as indicated by steps 518 and 501. Thus, if control of the display 106 of the gaming device 202 was transferred to the jackpot server 207, it is returned from the jackpot server 207 to the game controller 101 that controls play of the base game, as indicated in step 518. 25 In one embodiment, the bonus prize and the special prize are paid. In this embodiment, the gaming device 202 may display on the display a single combined prize representing the sum of the bonus prize and the special prize and displaying this as the result from the feature game. In another embodiment, when the special prize is to be awarded, it is awarded instead of the bonus prize. In this embodiment, all values of the special prize 14 are preferably higher than the advertised bonus prize for the feature outcome. Also in this embodiment the special prize need not be of the same type as the bonus prize, although it may be of the same type (e.g. both are prizes in credits). In both of these embodiments, the player may be presented with representations that indicate that the 5 bonus prize at least sometimes, or perhaps often depending on the particular implementation, is higher than the advertised amount. With continued play, the player may notice that when the prize varies from the advertised, the extent to which it is higher than the advertised prize also varies. When the special prize is awarded, the gaming machine may display a special 0 sequence on a display 106, play a sound and/or otherwise distinguish the prize from the normal bonus prize associated with the feature outcome. In one embodiment, whether or not a special sequence, sound or other distinguishing media is presented to the player when the special prize is awarded, no additional display of symbols representative of the random selection process in step 514 is made by the gaming 5 device 202. In an alternative embodiment, the special prize may be displayed separately to the bonus prize. This creates a different impression to the player, who sees that they have won the advertised prize for the feature game outcome (or bonus feature in the embodiment where a feature game is omitted) and with continued play sees that a 20 separate prize is awarded at random. Clearly, the player's eligibility for a special prize, as indicated in step 512, can be assessed on various bases. For example, each time a player is awarded a feature game the system may generate an additional special prize, of varying amounts, as randomly determined. Alternatively, only those players who win a particular bonus prize, 25 for example the lowest available bonus prize in the embodiment where every play of the feature game results in a prize, may be eligible for the special prize, somewhat in the manner of a consolation for the player. A further alternative would be for the player to be awarded a special prize in conjunction with all feature outcomes, but the quantum of the special prize that can be awarded might vary between say a very low prize or prize 30 range, and a quite significant prize or prize range. Eligibility may also be dependant on 15 the player placing an additional bet during play of the game in which the bonus feature may occur. An alternative embodiment to the process shown in Figure 5 is for the player to be awarded a special prize where a bonus feature has occurred but where no feature 5 game is played and consequently no feature game outcome is achieved. The eligibility for the special prize may for example be dependent on which bonus feature has occurred. Eligibility for the special prize is therefore not tied to the provision of a feature game. In this embodiment, when the bonus feature occurs, the player may be directly awarded 0 a bonus prize and is also eligible to be awarded the randomly awarded special prize. For example, a gaming machine may maintain a plurality of progressive prizes or a plurality of linked gaming machines may communicate with a progressive controller, which may be the jackpot controller 207, to maintain a plurality of progressives, the game controller 101 selecting one of the bonus prizes at random according to a 5 weighted selection process. The selection process for the bonus prizes may be similar to the selection process described herein below for the special prize. However, those skilled in the relevant arts will appreciate that alternative processes exist and could be developed. In this alternative embodiment, each progressive prize may be awarded as a bonus 20 prize when a particular combination occurs during play of a game. A single particular combination may be used as the bonus feature, following which the player could be awarded any one of the bonus prizes. Alternatively or in addition, different combinations may result in the award of different progressive prizes. In another example, the gaming machine or linked gaming machines 25 may offer a plurality of different fixed prizes on the occurrence of a bonus feature, there being a random selection of which fixed prize is won when the bonus feature occurs. By way of example, one of the progressive prizes may be awarded with three "J" symbols occur along a pay line of a spinning reel game. This progressive prize may be 16 constrained, either statistically and/or by fixed constraints to be within a certain range. When three "J" symbols occur along a pay line, the gaming machine or the progressive controller if provided may cause the award of that progressive prize. In addition, the gaming machine, the progressive controller or another device that receives a 5 communication notifying of the occurrence of the three "J" symbols randomly awards a special prize. It is envisaged that one manner of implementing the gaming system would be that a proportion of the revenue from each gaming machine would contribute towards a progressive prize pool which would then be distributed back to players via the prize 0 awarding system described above, on a random or quasi random basis. In an alternative embodiment, the special prize may be in the form of a payment by the gaming machine operator that is not incorporated into the return to player calculations. For a linked gaming system, the jackpot server 207 may incorporate a random number generator 113 which allocates special prizes to different players, depending on the 5 random number selected once a player achieved a feature outcome. The special prize awarding system could be revenue neutral, that is, over time, the system could be programmed to return to players all of the funds contributed by individual machines, but in different value amounts, in the manner described above. Thus, the volatility of the system would increase, yet the overall return to player percentage would remain 20 consistent. The random determination may instead be made by a random number generator 113 located in the housing of the gaming device 202 and may also be the same RNG 113 used for other aspects of game play. One means of prize awarding incorporating a random number generator 113 might be as follows: 25 The random number generator 113 might have say, 5000 available numbers for selection each time a player becomes eligible for a special prize. Numbers 1 to 1000 might be allocated as a zero prize, numbers 1001 to 2000 might be allocated as a first level of prize, numbers 2001 to 3000 might be allocated a second level of prize and so on. Of course, there are a wide variety of ways of randomly awarding amounts to 17 players on the occurrence of a triggering event, and the above example is intended to be simply illustrative of how the invention might be put into effect. Step 512 of the process would then involve the random number generator 113 selecting a number between 1 and 5000 which would then determine whether a prize was to be awarded, 5 and if so, the quantum of the prize. It is envisaged that the system will greatly increase a player's interest in the game because if, in normal play, after the bonus feature has been triggered, the feature game has been played resulting in the feature game outcome associated with the lowest bonus prize, once the feature game outcome is known, the player still has a second 0 opportunity to win, thereby increasing the player's enjoyment and anticipation in the feature game and feature outcome. The system can be implemented without changing the return to player percentage of a gaming machine, if it is implemented on a stand alone machine, or a gaming system, if implemented across a plurality of linked gaming machines controlled by a central 5 jackpot controller within a jackpot pool. 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 apparatus and machines, those skilled in the relevant arts will appreciate that the present invention also may have application to internet gaming and/or have application 20 to gaming over a telecommunications network, where handsets are used to display game outcomes and receive player inputs. 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 25 constitute various alternative aspects of the invention.

Claims (25)

1. A gaming machine having a display and a user interface in communication with a game controller, which cooperate to provide a game in which a plurality of symbols from a symbol set are displayed on the display to represent at least one game 5 outcome that is evaluated for a winning combination and in which an award is awarded if a winning combination results, wherein a said winning combination is a bonus feature, the occurrence of which results in the game controller controlling game play of the game to provide at least a chance to win a bonus prize from a set of one or more bonus prizes, the game controller further controlling the gaming 0 machine to evaluate any bonus prizes awarded in the bonus feature to determine whether an eligibility criterion for a special prize has been met and in response to determining that the eligibility criterion has been met, additionally award the special prize, wherein the special prize is different from the awarded bonus prize(s) and has a value which is, at least in part, determined using a random selection process. 5

2. The gaming machine of claim 1, wherein the gaming machine does not display on the display symbols representative of the random selection process.

3. The gaming machine of claim 1 or claim 2, wherein the gaming machine includes a pay schedule that advertises each of the one or more bonus prizes available in the bonus feature but does not advertise the at least one special prize. 20

4. The gaming machine of any one of the preceding claims, wherein the special prize is automatically awarded in response to the eligibility criterion being met.

5. The gaming machine of any one of claims 1 to 4, wherein there are at least two said bonus prizes that are winnable following occurrence of said bonus feature.

6. The gaming machine of claim 5, wherein the plurality of different bonus prizes 25 include a plurality of progressive prizes that are formed so as to have different values from each other.

7. The gaming machine of claim 5, wherein the plurality of different bonus prizes include a plurality of fixed value prizes of different values. 19

8. The gaming machine of claim 6 or claim 7, wherein the game controller selects each of the plurality of different bonus prizes with different average expected frequencies.

9. The gaming machine of any one of claims 5 to 8, wherein the bonus feature always results in the award of a positive value bonus prize. 5

10.The gaming machine of any one of claims 5 to 9, wherein the eligibility criterion requires that at least one, but not all of the bonus prizes are won.

11.The gaming machine of claim 10, wherein the special prize is awardable when a first said bonus prize is won and not awardable when a second said bonus prize is won, the second said bonus prize having a higher value than the first said bonus prize. 0

12. The gaming machine of claim 11, wherein the special prize is awardable only when the bonus prize of lowest value is won.

13.The gaming machine of any one of the preceding claims 1 to 12, wherein the gaming machine displays the combined special prize and bonus prize as a single prize and does not display separate indications of each prize. 15

14.A gaming machine according to any one of the preceding claims where in the award of the special prize is additionally dependant on the player placing an additional bet.

15.A gaming machine according to any one of the preceding claims, wherein there are a plurality of distinct bonus features representing different winning outcomes and wherein each bonus feature resulting in at least a chance to win a bonus prize from 20 a different set of one or more bonus prizes.

16.The gaming machine of claim 15, wherein the plurality of bonus features each result in a chance to win one of a plurality of different bonus prizes.

17. The gaming machine of any one of the preceding claims, wherein on occurrence of a bonus feature, the game controller commences play of a feature game in which 25 representations of the feature game are displayed on the display that indicate to the player the bonus prize that is to be awarded. 20

18.A gaming system including a plurality of gaming machines as claimed in any one of the preceding claims, wherein each of the plurality of gaming machines are eligible to win the same said one or more bonus prizes when a said bonus feature occurs on that gaming machine. 5

19.The gaming system of claim 18, wherein at least one of the one or more bonus prizes is a progressive prize to which each of the plurality of gaming machines contribute.

20.A method of providing awards on a gaming machine that provides a wagering game in which a plurality of symbols from a symbol set are displayed on a display to 0 represent play of the wagering game, the method including providing as one possible outcome of the game a bonus feature; when the bonus feature occurs, providing at least a chance to win a bonus prize from a set of one or more bonus prizes; and when the bonus feature occurs, evaluating any bonus prizes awarded in the bonus feature to determine whether an eligibility criterion for a special prize has 15 been met and in response to determining that the eligibility criterion has been met, additionally awarding the special prize, wherein the special prize is different from the awarded bonus prize(s) and has a value which is, at least in part, determined utilising a random selection process.

21.The method of claim 20, wherein the set of bonus prizes comprises a plurality of 20 bonus prizes of different value and wherein the eligibility criterion requires that a particular one of the bonus prizes has been awarded in the bonus feature.

22.The method of claim 21, wherein the process of providing a chance to win a bonus prize includes selecting which one of the plurality of bonus prizes is to be won, the selection being controlled so that a bonus prize is always won when the bonus 25 feature occurs.

23.The method of any one of claims 20 to 22, further including advertising in a pay schedule for the game the plurality of bonus prizes but not the special prize and performing the random selection process without displaying to a player symbols representing the result of the random selection process. 21

24. The method of any one of claims 20 to 23, further including awarding a single prize as a combination of a said bonus prize and the special prize and displaying representations of the award of the special prize as if the combination of a said bonus prize and the special prize was a single prize resulting from occurrence of the 5 bonus feature.

25.The method of any one of claims 20 to 24, further including displaying a feature game between occurrence of the bonus feature and the award of the special prize, the feature game including representations that indicate a said bonus prize that is to be awarded if a special prize is not awarded.