Patent Publication Number: US-8118661-B2

Title: Gaming machine

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is based upon and claims a priority from the U.S. provisional Patent Application No. 61/013,385 filed on Dec. 13, 2007, the entire contents thereof are incorporated herein by reference. 
    
    
     BACKGROUND 
     1. Technical Field 
     The present invention encompassing one or more aspects thereof relates to a gaming machine comprised of a plurality of stations. More particularly, it relates to a gaming machine wherein a game result is determined and a game can be executed independently for each of the stations. 
     2. Description of Related Art 
     Various gaming machines have conventionally been installed in game arcades and the like. As one of the examples of them, stand-alone-type gaming machines have been available. In such stand-alone-type gaming machines, a game result is determined for a gaming machine separately, i.e., a game for the single gaming machine is executed separately from games for other gaming machines. That is, a game for this type of gaming machine can go with a single gaming machine (i.e., a processor for determining a game result) and a player seated thereat. Each stand-alone-type gaming machine independently executes a game and decides a result of the game, even if a plurality of gaming machines is installed. As a result, games thereof become monotonous, making it difficult to have players play games continuous long time without letting them get bored. 
     As one aspect of gaming machines to be installed in game arcades and the like, a gaming machine comprised of a plurality of consoles has been available. In such a gaming machine, a game (e.g., baccarat, poker, and the like) is executed with a player seated at each of the plurality of consoles and a processor. That is, in the gaming machine, the processor determines a game result common to each of the plurality of consoles. For example, in case of baccarat, the processor determines a game result from any one of choices, namely, “TIE”, “BANKER” and “PLAYER” so as to serve as a dealer. Players anticipate a game result to be determined by the processor and carry out bet operation using gaming values at their respective consoles. In case the game result coincides with an anticipation on which a player has bet, the player can win a predetermined valued prize. 
     That is, the gaming machine comprised of the plurality of the consoles executes a game with each of the players and the processor, similar to the stand-alone-type gaming machine. In this regard, in the gaming machine comprised of the plurality of the consoles, a plurality of players seated at their respective consoles share a game result. However, even if a single game result is shared with plural players, a game content of one player does not influence game results of the other players. That is, the gaming machine comprised of the plurality of the consoles always executes a game and decides a result of the game in each of the plurality of the consoles, similar to the above-mentioned stand-alone-type gaming machine. As a result, there has been a same kind of problems as the above. 
     The object of the present invention is to provide a gaming machine capable of executing a game of which entertaining characteristics are novel to characteristics of conventional games with an event game of which contents are changed depending on the operation condition of the stations, executed by a plurality of stations, in addition to base games. 
     SUMMARY 
     Therefore, in order to achieve the object, according to a gaming machine of the present invention encompassing one or more aspects thereof, there is provided a gaming machine. The gaming machine comprises plural stations and a processor. Each of the plural stations determines a game result and executes a base game independently. The processor executes a base game independently at each station. The processor obtains an operation status of each station. The processor selects an event game among a plurality of event games based on the operation status of each station obtained thereby when a predetermined condition is satisfied. The processor executes the event game selected thereby in common at plural stations. As a result, in the above gaming machine, an event game in which the content of the game is changed according to the operation rate is executed at each of the plural stations. Thereby, the gaming machine can provide the player with new interest to the game which differs from the base game. 
     According to the present invention encompassing one or more aspects, there is provided a gaming machine. The gaming machine comprises plural stations and a processor. Each of the plural stations determines a game result and executes a base game independently. The processor executes a base game independently at each station. The processor obtains an operation status of each station. The processor calculates an operation rate of a gaming machine with the operation status of each station obtained thereby. The processor selects an event game among a plurality of event games based on the operation rate calculated thereby when a predetermined condition is satisfied. The processor executes the event game selected thereby in common at plural stations. As a result, in the above gaming machine, an event game in which the content of the game is changed according to the operation rate is executed at each of the plural stations. Thereby, the gaming machine can provide the player with new interest to the game which differs from the base game. 
     Furthermore, according to the present invention encompassing one or more aspects, there is provided a gaming machine. The gaming machine comprises plural stations and a processor. Each of the plural stations determines a game result and executes a base game independently. The processor executes a base game independently at each station. The processor obtains an operation status of each station. The processor calculates an operation rate of a gaming machine with the operation status of each station obtained thereby. The processor selects an event game to be jointly operated at each station among a plurality of event games when the operation rate calculated thereby is higher than a predetermined rate. The processor selects an event game to be independently operated at each station among a plurality of event games when the operation rate calculated thereby is lower than a predetermined rate. The processor executes the event game selected thereby in common at plural stations. As a result, in the above gaming machine, an event game in common with plural stations is executed at each of the plural stations when the operation rate is high. Thereby, the gaming machine can provide the player with new interest to the game which differs from the base game. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The accompanying drawings, which are incorporated in and constitute a part of this specification illustrate embodiments of the invention and, together with the description, serve to explain the objects, advantages and principles of the invention. 
         FIG. 1  is a flowchart of an event game select process program according to one embodiment of the present invention; 
         FIG. 2  is an external view of a gaming machine according to one embodiment of the present invention; 
         FIG. 3  is an external view of a station according to one embodiment of the present invention; 
         FIG. 4  is an explanatory view concerning a variety of symbols according to one embodiment of the present invention; 
         FIG. 5  is an explanatory view showing one example of a reel according to one embodiment of the present invention; 
         FIG. 6  is an explanatory view showing a control system of a gaming machine according to one embodiment of the present invention; 
         FIG. 7  is an explanatory view concerning a control system of a station according to one embodiment of the present invention; 
         FIG. 8  is an explanatory view concerning a configuration of a sub-control board installed in a station according to one embodiment of the present invention; 
         FIG. 9  is an explanatory view showing a display example of a main liquid crystal panel with scroll-displayed symbols thereon according to one embodiment of the present invention; 
         FIG. 10  is an explanatory view showing a display example of a main liquid crystal panel with repositioned symbols thereon according to one embodiment of the present invention; 
         FIG. 11  is an explanatory view showing a display example of a main liquid crystal panel with scroll-displayed symbols thereon while executing an independent event game according to one embodiment of the present invention; 
         FIG. 12  is an explanatory view concerning a payout table of a gaming machine according to one embodiment of the present invention; 
         FIG. 13  is a flowchart of a main control process program according to one embodiment of the present invention; 
         FIG. 14  is a flowchart of an event game monitoring process program according to one embodiment of the present invention; 
         FIG. 15  is a flowchart of a main control process program according to one embodiment of the present invention; 
         FIG. 16  is an explanatory view showing one example of tables which relates reel symbols to code numbers according to one embodiment of the present invention; 
         FIG. 17  is an explanatory view showing one example of tables which relates code numbers concerning reels to random number values, according to one embodiment of the present invention; 
         FIG. 18  is a flowchart of a joint-style event game execution process program according to one embodiment of the present invention; 
         FIG. 19  is an explanatory view concerning an event game point table according to one embodiment of the present invention; 
         FIG. 20  is a flowchart of an independent-style event game execution process program according to one embodiment of the present invention; and 
         FIG. 21  is an external view of a gaming machine according to one embodiment of the present invention. 
     
    
    
     DETAILED DESCRIPTION 
     The various aspects summarized previously may be embodied in various forms. The following description shows by way of illustration of various combinations and configurations in which the aspects may be practiced. It is understood that the described aspects and/or embodiments are merely examples, and that other aspects and/or embodiments may be utilized and structural and functional modifications may be made, without departing from the scope of the present disclosure. 
     It is noted that various connections are set forth between items in the following description. It is noted that these connections in general and, unless specified otherwise, may be direct or indirect and that this specification is not intended to be limiting in this respect. 
     A gaming machine, a server, and a game system according to one or more aspects of the invention will be described in detail with reference to the drawings based on an embodiment embodying one or more aspects of the invention. However, it is appreciated that one or more aspects of the present invention may be embodied in distributable (via CD and the like) or downloadable software games, console games, and the like. In this regard, the slot machine may be a virtual slot machine that is displayed on a multi-purpose computer and/or dedicated kiosk. Aspects of the invention are described by way of hardware elements. However, it is appreciated that these elements may also be software modules that are executable in a computer. The software modules may be stored on a computer readable medium, including but not limited to a USB drive, CD, DVD, computer-readable memory, tape, diskette, floppy disk, and the like. For instance, aspects of the invention may be embodied in a JAVA-based application or the like that runs in a processor or processors. Further, the terms “CPU”, “processor”, and “controller” are inclusive by nature, including at least one of hardware, software, or firmware. These terms may include a portion of a processing unit in a computer (for instance, in multiple core processing units), multiple cores, a functional processor (as running virtually on at least one of processor or server, which may be local or remote). Further, in network-based gaming systems, the processor may include only a local processor, only a remote server, or a combination of a local processor and a remote server. 
     It is contemplated that one or more aspects of the invention may be implemented as computer executable instructions on a computer readable medium such as a non-volatile memory, a magnetic or optical disc. Further, one or more aspects of the invention may be implemented with a carrier signal in the form of, for instance, an audio-frequency, radio-frequency, or optical carrier wave. 
     Next, a detailed description will be given on the inventive gaming machine as embodied in a gaming machine  100  by referring to drawings. 
     A gaming machine  100  directed to the present embodiment is constituted of a plurality of stations  1  (for instance, five stations). In the gaming machine  100 , each station  1  executes a base game independently (S 57  through S 62 ). Execution of this base game requires a player to bet a gaming value at random (S 57 ). 
     If predetermined conditions (S 16  and S 17 ) to be described later are satisfied, the gaming machine  100  selects an event game to be executed jointly in each station (S 31  through S 38 ). There are plural types of event game to be executed and the type of event game to be executed varies in accordance with the operation rate of the gaming machine  100 . Specifically, when the operation rate of the gaming machine  100  is the predetermined rate or more, the gaming machine  100  selects a game in which stations  1  entering the event game compete in order to obtain an event game payout which is a progressive payout. 
     Here, a schematic construction of the gaming machine  100  directed to the present embodiment will be described by referring to the drawings.  FIG. 2  is a perspective view showing an exterior appearance of the gaming machine  100  directed to the present embodiment. 
     As shown in  FIG. 2 , the gaming machine  100  has five stations  1 . Stations  1  are all mounted in line on an installation base  98 . In the gaming machine  100 , players execute different types of games (i.e., the base game and the event game to be described later) using the respective stations  1 . This installation base  98  houses an overall controller  91  and the like to be described later. 
     The gaming machine  100  also has a large display device  95  and a light emitting effect device  96 . The large display device  95  and the light emitting effect device  96  are mounted above the five stations  1  installed on the installation base  98 . The large display device  95  is a heretofore known large liquid crystal display and is adapted to display different types of game information (for instance, game rules and game score for each station  1 , or the like) in the gaming machine  100 . The light emitting effect device  96  has the effect of enhancing interest in the gaming machine  100  by emitting light in a predetermined fashion. 
     The large display device  95  and the light emitting effect device  96  are supported by a support member arranged at the back side of the installation base  98  (refer to  FIG. 2 ). Specifically, stations  1  installed on the installation base  98  are spaced away from the large display device  95  and the light emitting effect device  96 . Thus, according to the gaming machine  100 , the manager, etc. of the game arcade can replace the stations  1  on the installation base  98  without the need to remove the large display device  95  and the light emitting effect device  96 . 
     Next, stations  1  composing the gaming machine  100  directed to the present embodiment will be described in detail by referring to the drawings.  FIG. 3  is a perspective view showing an external appearance of one station  1  composing the gaming machine  100 . 
     Station  1  directed to the present embodiment is a so-called hybrid-type slot machine. This hybrid-type slot machine has a heretofore known transparent liquid crystal panel arranged at a front face of a plurality of mechanical reels that are rotatably supported. This hybrid-type slot machine displays images of different types of symbols drawn on an outer surface of the mechanical reels, while the transparent liquid crystal panel is in a transmission state upon execution of the game. 
     Station  1  directed to the present embodiment is an upright-type slot machine used in game arcades such as casinos and the like. This station  1  has a cabinet  2 , a main door  3  and a topper effect device  4 . The main door  3  is arranged at a front face of the cabinet  2 . The topper effect device  4  is arranged at an upper side of the cabinet  2 . 
     Cabinet  2  is a housing portion that houses the electrical and mechanical components for executing a predetermined game mode in station  1 . Cabinet  2  has three reels (specifically, left reel  5 , center reel  6  and right reel  7 ) which are rotatably provided therein. Reels  5  through  7  each have a symbol column drawn on an outer periphery thereof (refer to  FIG. 5 ). The symbol column is constituted of a predetermined number of symbols (for instance, blue seven symbol  90 A and the like to be described later). A main liquid crystal panel  11 B to be described later is arranged in front of the reels  5  though  7 . 
     The main door  3  has an upper display portion  10 A, a variable display portion  10 B and lower display portion  10 C provided as a display portion  10  for displaying information with respect to the game. The upper display portion  10 A is constituted of an upper liquid crystal panel  11 A arranged above the variable display portion  10 B. The upper liquid crystal panel  11 A displays, for instance, effect images, introduction to game contents, explanation of game rules, and the like. 
     The variable display portion  10 B is constituted of the main liquid crystal panel  11 B and is adapted to display an execution state of the game. The main liquid crystal panel  11 B is a heretofore known transparent liquid crystal panel secured to the main door  3 . 
     The main liquid crystal panel  11 B has three display windows  15 ,  16  and  17  formed therein (refer to  FIG. 3 ). Station  1  renders the back side of the display windows  15 ,  16  and  17  visible by placing these display windows in a transmission state. As a result, a player can visually recognize the symbols drawn on reels  5  through  7  via the respective display windows  15  through  17  (refer to  FIG. 9  and  FIG. 10 ). 
     As shown in  FIG. 3 , etc., one pay line L is displayed on the main liquid crystal panel  11 B in the variable display portion  10 B. This pay line L is a line that runs in a horizontal direction across a mid portion of the symbol display area corresponding to reels  5  through  7  and defines a symbol combination. Accordingly, if the symbol combination that was repositioned on the pay line L is a predetermined winning combination, the station  1  awards a payout in accordance with the winning combination and the credit amount that was bet (bet amount). 
     The number of reels may be five, instead of three, and further, the number of displayed symbols is not limited to nine symbols. 
     A touch panel  18  is provided at a front face of the main liquid crystal panel  11 B. Thus, the player can input different types of commands by operating of the touch panel  18 . In the present embodiment, the touch panel  18  is used at the time of an entry operation with respect to an event game to be described later. 
     A payout amount display portion  19  and a credit amount display portion  20  are provided at a right lower part of the variable display portion  10 B. The payout amount display portion  19  displays the payout amount and the like as the awarded payout amount. The payout amount display portion  19  displays a payout amount which is awarded if the symbol combination repositioned on the pay line L in a base game is a predetermined combination. On the other hand, the credit amount display unit  20  displays the credit amount that an actual player has. 
     The lower display portion  10 C is arranged below the variable display portion  10 B. This lower display portion  10 C is constituted of a plastic panel  11 C onto which an image is printed. In the lower display portion  10 C, the plastic panel  11 C is illuminated by backlights. 
     An operation table  25  is provided at a front face of the cabinet  2 . The operation table  25  is arranged between the variable display portion  10 B and the lower display portion  10 C so as to protrude towards the front side. A plurality of types of operation buttons  26  are arranged on this operation table  25 . Operation buttons  26  include a BET button, a collecting button, a start button and a CASHOUT button and the like. The operation table  25  has a coin insertion slot  27  and a bill insertion portion  28 . The coin insertion slot  27  accepts coins representing a gaming value inside the cabinet  2 . The bill insertion slot  28  accepts bills inside the cabinet  2 . 
     In the gaming machine  100  (i.e., including station  1 ) directed to the present embodiment, coins, bills or electronic valuable information (credit) corresponding to these are used as gaming values. However, the gaming values applicable to this invention are not limited to these items and may also include medals, tokens, electronic money or tickets, for instance. 
     Also, a coin tray  29  is provided at a lowermost portion of the cabinet  2 . This coin tray  29  receives the coins paid out by a hopper  64 . A light emitting portion  30  is arranged at a periphery of cabinet  2  in station  1 . The light emitting portion  30  lights up in a predetermined lighting fashion in the event of a win or during the event game. A speaker  31  is provided at a side face of the cabinet  2  and is adapted to output sounds in accordance with the progress of the game. 
     Station  1  also has a topper effect device  4  provided at an upper side of cabinet  2 . This topper effect device  4  has a rectangular board shape and is arranged so as to become substantially parallel with the upper display portion  10 A. 
     Next, the symbols in the gaming machine  100  directed to the present embodiment will be described by referring to the drawings.  FIG. 4  is an explanatory diagram of the respective symbols employed by the gaming machine  100  directed to the present embodiment. 
     As shown in  FIG. 4 , the gaming machine  100  employs six types of symbols during the game. The six types of symbols are constituted of a blue seven symbol  90 A (BLUE 7), a red seven symbol  90 B (RED 7), a triple bar symbol  90 C (3-BAR), a double bar symbol  90 D (2-BAR), a bar symbol  90 E (BAR) and a blank symbol  90 F (BLANK). 
     These six types of symbols constitute a symbol column when a predetermined number thereof are positioned in array (refer to  FIG. 5 ). The reel bands of the left reel  5 , the center reel  6  and the right reel  7  each contain a corresponding symbol column. In the symbol columns, the above described symbols are each positioned in a predetermined sequence. Accordingly, in the base game and the event game, station  1  can reposition the symbols while scrolling through the respective display windows  15  through  17  of the main liquid crystal panel  11 B. 
     The blue seven symbol  90 A through the bar symbol  90 E constitute a winning combination if three of them are repositioned in a predetermined fashion on the pay line L of the main liquid crystal panel  11 B. In this case, the gaming machine  100  awards a predetermined payout amount to the player based on the relevant winning combination (refer to  FIG. 12 ). 
     Next, the internal construction of the gaming machine  100  directed to the present embodiment will be described in detail by referring to the drawings.  FIG. 6  is a block diagram showing an internal construction of the gaming machine  100 . 
     As shown in  FIG. 6 , the gaming machine  100  is provided with an overall controller  91 . This overall controller  91  executes a control program to be described later (for instance, an event game start process program, etc.) to control the entire gaming machine  100 . The overall controller  91  functions as a processor for the gaming machine directed to the present invention, together with controller  41  of each station  1 . 
     The overall controller  91  is constituted of an overall control CPU  92 , an overall control ROM  93  and an overall control RAM  94 . The overall control ROM  93  stores a control program and a data table required for controlling the entire gaming machine  100 . Accordingly, this overall control ROM  93  stores a main process program to be described later (refer to  FIG. 13 ) and an event game monitoring process program (refer to  FIG. 14 ) and the like. The overall control CPU  92  is a central processing unit that executes the various types of control programs stored in the overall control ROM  93 . The overall control CPU  92  serves as the core for controlling the entire gaming machine  100 . 
     The overall control RAM  94  temporarily stores the computed results and the like when the overall control CPU  92  executes a control program. This overall control RAM  94  also stores event game payout information. The event game payout information shows the payout amount for the event game payout awarded in a certain event game. This event game payout is a progressive payout as will be described later. Accordingly, this event game payout information stored in the overall control RAM  94  is renewed as needed upon reception of bet information and the like from each station  1 . Further, this overall control RAM  94  stores used credit information for each station  1 . This used credit information shows the overall credit amount (i.e., the bet amount) which was bet when the base game is executed. Accordingly, the used credit information is renewed as needed upon reception of bet information from each station  1 . 
     The five stations  1  constituting the gaming machine  100  are each connected to the overall controller  91 . Thus, the overall controller  91  can transmit and receive different types of data to/from each one of the five station  1 . The overall controller  91  can thus control each station  1  based on the control program stored in the overall control ROM  93 . Specifically, the overall controller  91  can control the event game with respect to the entire gaming machine  100  by executing an event game monitoring process program to be described later. 
     A timer  97  serving as a timing device is connected to the overall controller  91 . This timer  97  is referenced when judging whether one of the event game start conditions is satisfied in an event game monitoring process program. This timer  97  is also referenced when judging the lapse of an event game execution period (hereinafter referred to as event game period). 
     Next, the internal construction of station  1  directed to the present embodiment will be described in detail by referring to the drawings.  FIG. 7  is a block diagram showing the internal construction of station  1 . 
     As shown in  FIG. 7 , station  1  has a plurality of constituting elements, with a main control board  71  as a core. The main control board  71  has a controller  41  for executing control programs and the like to be described later ( FIG. 15 ,  FIG. 18  and  FIG. 20 ). As was described in the above, the controller  41  functions as a processor in the present invention, together with the overall controller  91 . 
     Controller  41  has a main CPU  42 , a RAM  43  and a ROM  44 . The main CPU  42  inputs/outputs signals to/from the other constituting elements through an I/O port  49  to execute a program stored in ROM  44 . The main CPU  42  thus serves as the core for controlling station  1 . RAM  43  temporarily stores data and programs to be used when the main CPU  42  is operational. For instance, RAM  43  temporarily stores random number values which were sampled by a sampling circuit  46  to be described later. ROM  44  stores permanent data and programs to be executed by the main CPU  42 . 
     More particularly, the programs stored in ROM  44  include a game program and a game system program (hereinafter referred to as a game program, etc.). Further, this game program also includes a lottery program. The lottery program serves to decide code numbers for each reel  5  through  7 . These code numbers correspond to symbols each repositioned on the pay line L, as will be described later. 
     The main control board  71  has the controller  41 , a random number generation circuit  45 , a sampling circuit  46 , a clock pulse generation circuit  47  and a divider  48 . 
     The random number generation circuit  45  operates in response to a command from the main CPU  42  to generate random numbers in a definite range. The sampling circuit  46  extracts an arbitrary random number from the random numbers generated by the random number generation circuit  45  in response to a command from the main CPU  42 . The sampling circuit  46  inputs the extracted random number to the main CPU  42 . The clock pulse generation circuit  47  generates a reference clock for activating the main CPU  42 . Then, the divider  48  inputs a signal obtained by dividing the reference clock by a fixed period, to the main CPU  42 . 
     A reel driving unit  50  is connected to the main control board  71 . This reel driving unit  50  has a reel position detection circuit  51  and a motor driving circuit  52 . The reel position detection circuit  51  detects the stop position for each one of the left reel  5 , the center reel  6  and the right reel  7 . The motor driving circuit  52  inputs a driving signal to motors M 1 , M 2  and M 3  which are connected to reels  5  through  7 , respectively. Motors M 1 , M 2  and M 3  are activated in response to a driving signal inputted from the motor driving circuit  52 . As a result, motors M 1 , M 2  and M 3  respectively spin reels  5  through  7 , and stop them at a desired position. 
     A touch panel  18  is also connected to the main control board  71 . This touch panel  18  identifies the coordinate position of the portion a player has touched. The touch panel  18  identifies where the player touched the panel and in which direction the touched location has moved based on the identified coordinate position information. The touch panel  18  inputs a signal corresponding to the identification results to the main CPU  42  through the I/O port  49 . 
     Operation buttons  26  are also connected to the main control board  71 . As was already described, the operation buttons  26  include a start button for instructing execution of the game, a collecting button, a BET button, etc. The buttons included in the operation buttons  26  each input an operation signal to the main CPU  42  through the I/O port  49  upon being held down. 
     A communication interface  68  is connected to the main control board  71 . This communication interface  68  is employed during transmission and reception of different types of data (for instance, bet information, game results of the event game, etc.) between the station  1  and the overall controller  91 . 
     The main control board  71  also has an illumination effect driving circuit  61 , a hopper driving circuit  63 , a payout completion signal circuit  65  and a display portion driving circuit  67 . 
     The illumination effect driving circuit  61  outputs an effect signal with respect to the above-described light emitting portion  30  and the topper effect device  4 . The topper effect device  4  is connected in series with the illumination effect driving circuit  61  through the light emitting portion  30 . When an effect signal is received, the light emitting portion  30  and the topper effect device  4  emit light in a predetermined light emitting pattern. As a result, station  1  has an illumination effect in accordance with the progress of the game. 
     The hopper driving circuit  63  drives a hopper  64  based on the control of the main CPU  42 . As a result, the hopper  64  performs a coin payout operation whereby coins are paid out to the coin tray  29 . The display portion driving circuit  67  then controls display of the respective display portions including the payout amount display portion  19 , the credit amount display portion  20  and the like. 
     As shown in  FIG. 7 , a coin detecting portion  66  is connected to the payout completion signal circuit  65 . The coin detecting portion  66  measures the number of coins paid out by the hopper  64  and then inputs data on the measured amount of coins to the payout completion signal circuit  65 . The payout completion signal circuit  65  judges whether a set number of coins has been paid out, based on the coin amount data inputted from the coin detecting portion  66 . If the set number of coins has been paid out, the payout completion signal circuit  65  inputs a signal showing completion of coin payout to the main CPU  42 . 
     As shown in  FIG. 7 , a sub-control board  72  is connected to the main control board  71 . This sub-control board  72  is composed on a circuit board that differs from the main control board  71 . The sub-control board  72  controls display of the upper liquid crystal panel  11 A and the main liquid crystal panel  11 B and controls sound output by speaker  31  based on a command inputted from the main control board  71 . 
     The sub-control board  72  has a micro computer (hereinafter referred to as a sub-micro computer  73 ) as a main constituting element thereof. The sub-micro computer  73  has a sub-CPU  74 , a program ROM  75 , a work RAM  76 , and I/O ports  77  and  80 . The sub-CPU  74  performs a control operation in accordance with a control command transmitted from the main control board  71 . The program ROM  75  stores a control program executed by the sub-CPU  74 . The work RAM  76  is constituted as a temporary storage section for use when the above control program is executed by the sub-CPU  74 . 
     The sub-control board  72  executes random number sampling upon an operation program of the sub-CPU  74 . The sub-control board  72  carries out processes similar to those of the clock pulse generation circuit  47 , the divider  48 , the random number generation circuit  45  and the sampling circuit  46  provided on the main control board  71 . 
     The sub-control board  72  also has a sound source IC  78 , a power amplifier  79  and an image control circuit  81 . The sound source IC  78  controls the sound outputted from the speaker  31 . The power amplifier  79  amplifies the sound output. The image control circuit  81  operates as a display control section of the upper liquid crystal panel  11 A and the main liquid crystal panel  11 B. 
     The image control circuit  81  has an image control CPU  82 , an image control work RAM  83 , an image control program ROM  84 , an image ROM  86 , a video RAM  87  and an image control IC  88 . The image control CPU  82  decides the image to be displayed on the upper liquid crystal panel  11 A and the main liquid crystal panel  11 B in accordance with the image control program and the parameters set in the sub-micro computer  73 . 
     The image control program ROM  84  stores an image control program and different types of select tables relating to the display for the upper liquid crystal panel  11 A and the main liquid crystal panel  11 B. The image control work RAM  83  is a temporary storage section used when the image control program is executed in the image control CPU  82 . The image control IC  88  forms images according to the contents decided by the image control CPU  82  and outputs these images to the upper liquid crystal panel  11 A and the main liquid crystal panel  11 B. The image ROM  86  stores dot data for forming images. The video RAM  87  functions as a temporary storage section for use when an image is formed by the image control IC  88 . 
     Next, a description will be given on the base game and the event game executed in the gaming machine  100  according to the present embodiment. 
     First, the base game in the gaming machine  100  will be described. The base game is a slot game executed separately in each station  1 . Specifically, the base game is a slot game in which a payout is acquired by repositioning a specific symbol combination on a pay line L of reels  5  through  7 . 
     More specifically, when the base game starts, the player first operates the operation buttons  26  to set the number of bets. Then, when the player holds down the start button, reels  5  through  7  start spinning. The symbol columns drawn on the reels  5  through  7  are each scroll displayed in a downward direction in the display windows  15  through  17  each of which are in a transparent state (refer to  FIG. 9 ). 
     When a predetermined time has lapsed, reels  5  through  7  each stop automatically in a predetermined sequence. As a result, portions of the symbol columns (three symbols in each reel, a total of 9 symbols) drawn on each of the reels  5  through  7  are respectively repositioned in the respective display windows  15  through  17  which are in a transparent state (refer to  FIG. 10 ). 
     Here, in the base game, a payout amount is awarded when a predetermined type of winning combination is repositioned on the pay line L. The payout amount is calculated by multiplying the number of bets to the payout in accordance with the winning combination repositioned on the pay line L. 
     A unit game in the base game is composed of a series of processes ranging from betting of the gaming values to repositioning the symbols and payout (S 57  through S 62 ). 
     Next, the event game in the gaming machine  100  will be described. The event game according to the present embodiment is executed if predetermined conditions are satisfied. Here, the predetermined conditions include: “non-execution of an event game during a predetermined time (S 16 )”, and “event game payouts are equal to or above a predetermined amount (S 17 )”. If these conditions are satisfied, the event game is executed. 
     There are two types of game in the event games to be executed; a joint-style event game executed in each station cooperatively and an independent-style event game executed in each station separately. The operation rate of the gaming machine  100  determines the event game to be executed selectively (S 31  through S 38 ). More specifically, when the operation rate of the gaming machine  100  is 60 percent or more (i.e., at least three stations  1  are executing a base game), the joint-style event game is executed. Meanwhile, when the operation rate of the gaming machine  100  is less than 60 percent (that is, two stations  1  or less are executing a base game), an independent-style event game is executed. 
     Next, the joint-style event game is first described. In the joint-style event game, each one of a plurality (specifically, three or more) of stations  1  competes with the rest of the stations  1  for the superiority of game results in the event game. Accordingly, the joint-style event game corresponds to a game executed jointly by a plurality (specifically, three or more) of stations  1 . 
     The joint-style event game is constituted of a plurality of unit event games. More specifically, in the joint-style event game, each station  1  can execute the unit event game any number of times as long as it is within the predetermined time (hereinafter referred to as event game period). 
     In this unit event game, station  1  scroll-displays the symbols (S 72 ), after which it repositions the symbols based on the lottery results (S 72 ), similarly with the unit game in the above-described base game. Then, in the unit event game, “an event game point” is awarded based on three symbols repositioned on the pay line L. Specifically, the game results of the unit event game are the sum value of the event game points based on three symbols repositioned on the pay line L. This event game point is an index for judging the superiority of the game results in an event game. The event game point differs from the payout based on the winning combination and does not correspond to the gaming value (credit). 
     In the gaming machine  100  according to the present embodiment, when an entry to the joint-style event game is made, an entry fee is collected from the player through station  1  (S 19 ). After the entry fee is collected, the above station  1  starts the unit event game. Then, the station  1  executes the unit event game a plurality of times during the event game period. After the event game period has lapsed, the event game ends. 
     Thus, the game results of the joint-style event game are obtained by summing up the game results of the unit event game executed a plurality of times in the station  1 . Accordingly, the gaming machine  100  compares the game results of the event game in each station  1  with the total value of event game points acquired during the event game period. The station  1  with the best game results in the event game is then identified based on the results of this comparison. 
     Then, an event game payout is awarded in the joint-style event game with respect to the station  1  which obtained the best game results in the event game. This event game payout is a progressive payout. Specifically, the event game payout is constituted by accumulating and adding the gaming values corresponding to a predetermined ratio of the number of bets made upon execution of the base game, and the collected entry fee. 
     Next, the independent-style event game will be described. The independent-style event game is a so-called free game to be executed at a bonus game in a usual slot machine. The free game here is a game in which a slot game is executed repeatedly within a predetermined time without collecting a gaming value from a player. The contents of the free game are basically the same as the said base game, in which a payout is obtained by repositioning a predetermined symbol combination on the pay line L crossing respective reels  5  through  7 . Therefore, the independent-style event game corresponds to the game to be executed by a certain number of (i.e., at most two) stations  1  independently. 
     However, during the free game, reels  5  through  7  each start to rotate without a setting operation of a bet amount or an operation of a start button by a player, which is different from the base game (refer to  FIG. 11 ). When a predetermined time has lapsed, reels  5  through  7  each stop automatically in a predetermined sequence. 
     Here, in the free game, a payout amount is awarded when a predetermined type of wining combination is repositioned on the pay line L. The payout amount is calculated by multiplying the number of bets to the payout in accordance with the winning combination repositioned on the pay line L. The number of bets used is the number of bets betted at the most recent base game before the independent-style event game starts. 
     The independent-style event game ends when the predetermined time has lapsed, and returns to the base game. 
     Next, a detailed description will be given on the winning combinations and the associated payout amounts in the base game and the independent-style event game (free game) by referring to the drawings.  FIG. 12  is an explanatory diagram of a payout table showing the winning combinations and the payout amount for each winning combination according to the present embodiment. 
     The payout amounts shown in  FIG. 12  represent payout amounts for the case the number of bets is “1”. If the number of bets is “2” or more, the amount to be paid is obtained by multiplying the respective number of bets by a payout amount as shown in  FIG. 12 . 
     For instance, if three blue seven symbols  90 A are repositioned on the pay line L, an amount obtained by multiplying the number of bets by 1000 credits will be paid out. 
     If the three symbols repositioned on the pay line L are constituted of blue seven symbol  90  and red seven symbol  90 B, an amount obtained by multiplying the number of bets by 80 credits will be paid out. In this case, the blue seven symbol  90 A and the red seven symbol  90 B included in the three symbols on the pay line L may be positioned in any pattern. 
     The payout amount for each winning combination shown in  FIG. 12  is set in a similar manner. In this case, however, if the three symbols repositioned on the pay line L do not correspond to any of the winning combinations (refer to  FIG. 12 ), the game is a losing. In this case, no payout is made. 
     Next, the main control program to be executed in the gaming machine  100  according to the present embodiment will be described in detail by referring to the drawings.  FIG. 13  is a flow chart of the main control program. 
     This main control program controls the operation of the entire gaming machine  100 . Accordingly, the main control program is executed by the overall control CPU  92  of the overall controller  91 . 
     First, when the power-on switch of the gaming machine  100  is pressed (power is applied), the overall control CPU  92  executes an initial setting process (S 1 ). When the gaming machine  100  is turned on, power is supplied to each station  1 . 
     In this initial setting process (S 1 ), the overall control CPU  92  executes initial setting of the overall controller  91  and the like, and at the same time transmits an initial setting signal to the main CPU  42  of each station  1 . 
     Upon receiving this initial setting signal, each station  1  activates their main control board  71  and the sub-control board  72  to execute an initial setting. During the initial setting, the main CPU  42  of each station  1  executes the BIOS stored in ROM  44  to develop compressed data incorporated in the BIOS to the RAM  43 . The main CPU  42  then executes the BIOS developed in the RAM  43  and diagnoses and initializes the various types of peripheral devices. Further, the main CPU  42  writes the game program, etc. from the ROM  44  to the RAM  43  to obtain payout rate setting data and country ID information. During the initial setting, the main CPU  42  also carries out an authentication process with respect to each program. 
     When the initial setting in each station  1  is completed, the overall control CPU  92  shifts the process to S 2 . 
     After shifting to S 2 , the overall control CPU  92  transmits a game start signal to each station  1 . As will be described later, each station  1  can execute the base game and the event game upon receiving this game start signal. After the game start signal is transmitted to each station  1 , the overall control CPU  92  shifts the process to S 3 . 
     After shifting to process S 3 , the overall control CPU  92  executes an event game monitoring process. In this event game monitoring process (S 3 ), the overall control CPU  92  carries out an overall control process with respect to the execution of the event game, having as object the entire gaming machine  100 . For instance, the overall control CPU  92  carries out a renewal process of the event game payout information and the used credit information, a process with respect to the start conditions and end conditions of the event game, a process of selecting an event game, and a process with respect to awarding the event game payout. This event game monitoring process (S 3 ) will be described in detail later. When the event game monitoring process (S 3 ) is completed, the overall control CPU  92  executes the event game monitoring process again. 
     Next, an event game monitoring process program to be executed by the overall control CPU  92  will be described in detail by referring to the drawings.  FIG. 14  is a flow chart of the event game monitoring process program. 
     As shown in  FIG. 14 , when execution of the event game monitoring process program starts, the overall control CPU  92  first judges whether bet information was received (S 11 ). This bet information shows the amount of gaming values (i.e., number of bets) that was bet upon execution of the slot game in each station  1 . This bet information is transmitted from station  1  to the overall controller  91  by executing a start acceptance process, etc. (S 57  and S 58 ) to be described later. If the bet information was received (S 11 : YES), the overall control CPU  92  shifts the process to S 12 . On the other hand, if no bet information is received (S 11 : NO), the overall control CPU  92  shifts the process to S 13 . 
     After shifting to process S 12 , the overall control CPU  92  executes a data renewal process. In the data renewal process (S 12 ), the overall control CPU  92  renews the contents of the event game payout information and the used credit information based on the received bet information. More specifically, the overall control CPU  92  accumulates and adds the gaming values for a predetermined ratio (for instance, 2%) of the number of bets indicated to the bet information with the actual event game payout. As a result, the event game payout information is renewed. The overall control CPU  92  accumulates and adds the number of bets indicated in the received bet information with the number of credits of station  1  which transmitted the bet information. As a result, the used credit information of the respective stations  1  is renewed. After the event game payout information and the used credit information are renewed, the overall control CPU  92  shifts the process to S 13 . 
     In process S 13 , the overall control CPU  92  judges whether an initialization signal was received. The initialization signal is transmitted from station  1  if a bet is not made with respect to the base game during a predetermined time. The above initialization signal also instructs initialization of the used credit information. If the initialization signal was received (S 13 : YES), the overall control CPU  92  shifts the process to S 14 . On the other hand, if no initialization signal was received (S 13 : NO), the overall control CPU  92  shifts the process to S 15 . 
     In process S 14 , the overall control CPU  92  initializes the used credit information. At S 14 , the overall control CPU  92  first identifies the station  1  that transmitted the initialization signal based on the received initialization signal. Then, the overall control CPU  92  initializes the used credit information corresponding to the identified station  1 . As a result, the used credit information according to station  1  indicates “number of credits: 0”. After the used credit information was initialized, the overall control CPU  92  shifts the process to S 15 . 
     After shifting to process S 15 , the overall control CPU  92  judges whether the event game is being executed in the gaming machine  100 . More specifically, the overall control CPU  92  references timer  97  to judge whether the gaming machine  100  is within an event game period. If the event game is being executed (S 15 : YES), the overall control CPU  92  shifts the process to S 20 . In this case, the overall control CPU  92  monitors and controls the being-executed event game (S 20  through S 25 ). On the other hand, if the event game is not being executed (S 15 : NO), the overall control CPU  92  shifts the process to S 16 . In this case, the overall control CPU  92  monitors and controls the start of the event game (S 16  through S 19 ). 
     At S 16 , the overall control CPU  92  judges whether an interval period has lapsed. The interval period is a predetermined time from the end of the previous event game. Accordingly, at S 16 , the overall control CPU  92  references timer  97  to judge whether the time in which an event game was not executed is equal to or longer than a predetermined time. If the interval period has lapsed (S 16 : YES), the overall control CPU  92  shifts the process to S 17 . On the other hand, if the interval period has not lapsed (S 16 : NO), the overall control CPU  92  ends the event game monitoring process program as is. 
     After shifting to S 17 , the overall control CPU  92  references the overall control RAM  94  to determine whether the event game payout is equal to or above a predetermined amount. As was described in the above text, the event game payout is a progressive payout. Accordingly, the event game payout is renewed as needed through the above described data renewal process (S 12 ). If the event game payout is equal to or above a predetermined amount (S 17 : YES), the overall control CPU  92  shifts the process to S 18 . On the other hand, if the event game payout is below a predetermined amount (S 17 : NO), the overall control CPU  92  ends the event game monitoring process program as is. 
     At S 18 , the overall control CPU  92  executes an event game select process ( FIG. 1 ) to be later described. In the event game select process, the overall control CPU  92  obtains the operation status of each station, and based on the obtained operation status, selects an event game to be executed from the two types of event game (joint-style event game and independent-style event game). The details of the event game select process (S 18 ) will later be described referring to the drawings. 
     At S 19 , the overall control CPU  92  executes an event game start process. More specifically, the overall control CPU  92  first collects the entry fee from stations  1  which enter in the event game. The entry fee represents the counter value for entering the event game, and is collected as gaming value (credits). After collecting the entry fee, the overall control CPU  92  transmits the event game start signal with respect to the stations  1  which performed the entry operation. The event game start signal includes the information to identify the type of event game selected at S 18 . Simultaneously with the transmission of the event game start signal, the overall control CPU  92  references timer  97  and stores information showing the event game start time in the overall control RAM  94 . After transmitting the event game start signal, the overall control CPU  92  ends the event game monitoring process program. The entry fee is collected only from the station entering the joint-style event game. 
     Here, if the event game is executed (S 15 : YES), the overall control CPU  92  performs the judgment process at S 20 . At S 20 , the overall control CPU  92  judges whether the event game period has lapsed. More specifically, the overall control CPU  92  references the information for the event game start time stored in the overall control RAM  94  and timer  97  to judge whether the predetermined event game period has lapsed. If the event game period has lapsed (S 20 : YES), the overall control CPU  92  shifts the process to S 21 . On the other hand, if the event game period has not lapsed yet (S 20 : NO), the overall control CPU  92  ends the event game monitoring process program as is. 
     At S 21 , the overall control CPU  92  transmits an event game end signal to station  1 . The event game end signal shows the end of the event game. After the event game end signal is transmitted to station  1 , the overall control CPU  92  shifts the process to S 22 . 
     Upon receiving the event game end signal, the main CPU  42  of station  1  executes processes (S 75  through S 77 ) with respect to ending of the event game. 
     At S 22 , the overall control CPU  92  judges whether the event game which has ended is a joint-style event game or not. As a result, when judged that a joint-style event game has ended (S 22 : YES), the overall control CPU  92  shifts the process to S 23 . Meanwhile, when judged that an independent-style event game has ended (S 22 : NO), the overall control CPU  92  ends the event game monitoring process program as is. 
     At S 23 , the overall control CPU  92  executes an event game result judgment process. This event game result judgment process (S 23 ) serves to identify the station  1  with the best event game results based on the event game results of each station  1  which entered the joint-style event game. 
     More specifically, the overall control CPU  92  first receives event game result information from each station  1  which entered the joint-style event game. The event game result information is transmitted from stations  1  which received the event game end signal (S 75 ). As was described in the above text, the event game result information shows a sum value of the event game points acquired during the event game period. Accordingly, the overall control CPU  92  identifies the station  1  which acquired the most event game points (i.e., the payout object station) based on the event game result information of each station  1 . After identifying the payout object station, the overall control CPU  92  shifts the process to S 24 . 
     After shifting to S 24 , the overall control CPU  92  transmits the event game payout signal to the payout object station. This event game payout signal instructs payout of the event game payout of the joint-style event game with respect to station  1 . The event game payout signal includes information showing the event game payout amount renewed through the data renewal process (S 12 ). Accordingly, upon receiving the event game payout signal, the main CPU  42  of station  1  pays out to the player the event game payout. After transmitting the event game payout signal to the payout object station, the overall control CPU  92  shifts the process to S 25 . 
     In S 25 , the overall control CPU  92  initializes the event game payout information stored in the overall control RAM  94 . After that, the overall control CPU  92  ends the event game monitoring process program. 
     Next, the event game select process program will be described in detail by referring to the drawings.  FIG. 1  is a flow chart of the event game select process program. 
     After shifting to the event game select process (S 18 ), the overall control CPU  92  obtains the operation status of each station  1  composing the gaming machine  100  (S 31 ). The operation status serves as the information for identifying whether a station  1  is operating; in other words, whether the station  1  is executing the base game. More specifically, the overall control CPU  92  executes the process of S 31  by identifying the station  1  executing the base game based on the bet information received within a predetermined time (for instance, five minutes). 
     Next, at S 32 , the overall control CPU  92  calculates the operation rate of the gaming machine  100 . Specifically, the overall control CPU  92  calculates the percentage of the operating stations  1  in all the stations  1  based on the operation status of each station  1  obtained at S 31 . For instance, if three stations are operating, the operation rate is 60 percent. The overall control CPU  92  then shifts the process to S 33 . 
     At S 33 , the overall control CPU  92  judges whether the operation rate of the gaming machine  100  calculated at the above S 32  is equal to or more than the predetermined rate. The predetermined rate can be, for example, 60 percent. If the operation rate of the gaming machine  100  is equal to or more than the predetermined rate (S 33 : YES), the overall control CPU  92  shifts the process to S 34 . Meanwhile, if the operation rate of the gaming machine  100  is less than the predetermined rate (S 33 : NO), the overall control CPU  92  shifts the process to S 38 . 
     At S 34 , the overall control CPU  92  selects the joint-style event game as the event game to be executed at each of the stations  1 . The joint-style event game is an event game in which a plurality of stations  1  compete for the superiority of game results as was described in the above text. 
     Next, at S 35 , the overall control CPU  92  transmits an event game opening signal to the stations currently operating (i.e., executing the base game). After transmitting the event game opening signal, the overall control CPU  92  shifts the process to S 36 . As later described, upon receiving the event game opening signal, the main CPU  42  of the station executes an entry operation acceptance process (S 53 ) to be later described. In this case, the player directed to the station  1  can execute an entry operation with respect to the event game. 
     At S 36 , the overall control CPU  92  receives an event game entry signal. The event game entry signal serves to show the intention to enter the joint-style event game. The event game entry signal is transmitted from the station  1  in which an entry operation is executed at the entry operation acceptance process (S 53 ). The overall control CPU  92  receives an event game entry signal from stations  1  during a predetermined time. When the predetermined time has lapsed, the overall control CPU  92  shifts the process to S 37 . 
     After shifting to S 37 , the overall control CPU  92  judges whether equal to or more than the predetermined number of (for instance, three) stations  1  are entering the joint-style event game. More specifically, the overall control CPU  92  identifies the stations  1  entering the joint-style event game based on the event game entry signal. This enables the overall control CPU  92  to identify the number of stations  1  entering the joint-style event game, and to execute the judgment process of S 37 . If stations  1  of equal to or more than the predetermined number are entering the joint-style event game (S 37 : YES), the overall control CPU  92  ends the event game select process program in the condition the joint-style event game is selected. 
     Meanwhile, the number of stations  1  entering the joint-style event game is less than the predetermined number of stations (S 37 : NO), the overall control CPU  92  shifts the process to S 38 . 
     At S 38 , the overall control CPU  92  selects the independent-style event game as the event game to be executed at each of the stations  1 . The independent-style event game is a free game independently executed at each station  1  as was described in the above text. If the joint-style event game is already selected at S 34 , the independent-style event game is newly selected instead of the joint-style event game. After that, the overall control CPU  92  ends the event game select process program. 
     As above mentioned, the game contents directed to the event game are changed in accordance with the operation status of each station  1 . As a result, the above gaming machine  100  can provide new interest to the players which differs from the base game. 
     Next, the main game process program executed in each station  1  constituting the gaming machine  100  will be described in detail by referring to the drawings.  FIG. 15  is a flow chart of the main game process program executed in station  1 . 
     The game in station  1  according to the present embodiment (specifically, the base game, the event game) is realized by executing the main game process program. The main game process program is repeatedly executed during power supply to station  1 . 
     In the following description, each station  1  has already ended initial setting for each station  1  following reception of the initial setting signal transmitted from the overall control CPU  92 . 
     As shown in  FIG. 15 , after starting execution of the main game process program following initial setting, the main CPU  42  judges whether a game start signal is received (S 51 ). This game start signal is transmitted from the overall controller  91  (S 2 ). If a game start signal is received (S 51 : YES), the main CPU  42  shifts the process to S 52 . On the other hand, if the game start signal is not yet received (S 51 : NO), the main CPU  42  puts the process in standby. Specifically, station  1  maintains the standby state until a game start signal is received. 
     At S 52 , the main CPU  42  judges whether an event game opening signal was received. This event game opening signal is transmitted by the overall control CPU  92  if the joint-style event game is selected as the event game to be executed (S 35 ). If the event game opening signal is received (S 52 : YES), the main CPU  42  shifts the process to the entry operation acceptance process (S 53 ). On the other hand, if the event game opening signal is not received (S 52 : NO), the main CPU  42  shifts the process to S 54 . 
     At S 53 , the main CPU  42  executes an entry operation acceptance process. In this entry operation acceptance process (S 53 ), the main CPU  42  accepts the operation of a player showing entry to the event game (i.e., entry operation). The operation of the player showing entry was not made to the event game is referred to as non-entry operation. 
     More specifically, the main CPU  42  displays “a message urging entry to the event game” and “a message that an entry fee is required when executing the event game” on the main liquid crystal panel  11 B. 
     Further, the main CPU  42  displays a selection on the main liquid crystal panel  11 B with respect to entry to the event game (i.e., “select: entry” and “select: non-entry”). Accordingly, a player playing at station  1  can judge whether to enter the event game or not, appropriately. And the player can carry out the entry operation or the non-entry operation. 
     The entry operation and the non-entry operation are carried out using the touch panel  18 . Specifically, the player executes the entry operation by touching the touch panel  18  corresponding to the “select: entry” portion. The player executes the non-entry operation by touching the touch panel  18  at the “select: non-entry” portion. If the entry operation was executed, the main CPU  42  transmits an event game entry signal to the overall controller  91 . After transmitting the event game entry signal, the main CPU  42  shifts the process to S 54 . 
     If the non-entry operation was carried out, the main CPU  42  transmits the event game non-entry signal to the overall controller  91 . 
     After shifting to S 54 , the main CPU  42  judges whether the event game start signal was received. The event game start signal serves to start the event game. As was described in the above text, the event game start signal is transmitted from the overall controller  91  to the station  1  entering the event game, after the event game to be executed is selected (S 19 ). If the main CPU  42  has received the event game start signal (S 54 : YES), it shifts the process to S 63 . As a result, the above station  1  performs specific processes (S 63  through S 66 ) with respect to execution of the event game. On the other hand, if the main CPU  42  has not received the event game start signal (S 54 : NO), it shifts the process to S 55 . In this case, the above station  1  executes processes (S 55  through S 62 ) relating to execution of the base game. 
     First, the processes (S 55  through S 62 ) relating to the execution of the base game in the main game process program will be described. At S 55 , the main CPU  42  judges whether the data retention period has lapsed. The data retention period is the period in which used credit information for the above station  1  is held in the overall control RAM  94  without being initialized. If the data retention period lapsed (S 55 : YES), the main CPU  42  shifts the process to S 56 . On the other hand, if the data retention period has not lapsed (S 55 : NO), the main CPU  42  shifts the process to S 57 . 
     After shifting to S 56 , the main CPU  42  transmits the initialization signal to the overall controller  91 . After transmitting the initialization signal, the main CPU  42  shifts the process to S 57 . As was described in the above text, upon receiving this initialization signal, the overall control CPU  92  initializes the used credit information for the station  1  which transmitted the initialization signal (S 14 ). 
     At S 57 , the main CPU  42  performs a start acceptance process. In the start acceptance process (S 57 ), the main CPU  42  accepts a bet operation from the player. The above bet operation is carried out by inserting a coin or operating the BET button. In the start acceptance process, the main CPU  42  transmits a control signal to the sub-control board  72 . As a result, the display windows  15  through  17  of the main liquid crystal panel  11 B each shift to or are maintained in a transparent state by the sub-control board  72 . 
     After shifting to S 58 , the main CPU  42  judges whether the start button was operated. More specifically, the main CPU  42  makes the judgment at S 58  based on the presence or absence of a signal based on the input operation of the start button. 
     If the start button was operated (S 58 : YES), the main CPU  42  executes the predetermined process and shifts the process to S 59 . More specifically, the main CPU  42  stores the bet information based on the number of bets set at the start acceptance process (S 57 ) in RAM  43 . The main CPU  42  then transmits this bet information to the overall controller  91 . The main CPU  42  also subtracts the number of bets according to this bet information from the number of credits. 
     In addition, if the start button was operated (S 58 : YES), the main CPU  42  starts a new data retention period. In this case, the used credit information of the above station  1  is not initialized until the new data retention period which was started has lapsed. Accordingly, if the start acceptance process (S 57 ) for the base game and operation of the start button are continuously executed within the data retention period, the used credit information showing the number of credits used by the player is held in the overall control RAM  94  for a long period. 
     On the other hand, if the start button is not operated (S 58 : NO), the main CPU  42  returns the process to S 55 . As a result, the start acceptance process (S 57 ) is executed again. Accordingly, the player can execute a bet number correction operation, etc. 
     In the next process S 59 , the main CPU  42  executes the symbol lottery process. This symbol lottery process (S 59 ) serves to decide the symbols positioned on the main liquid crystal panel  11 B by lottery. More concretely, the main CPU  42  executes the above lottery program to sample a random number value from the numerical range of a predetermined random number value range. The main CPU  42  decides each symbol (i.e., the stop position of reels  5  through  7 ) positioned on the pay line L based on the sampled random number values and the table. 
     Here, a process using the random number values in the symbol lottery process (S 59 ) will be described based on the drawings.  FIG. 16  is one example of tables showing associations between the symbols drawn on one reel band and code numbers.  FIG. 17  is one example of tables showing the association between random number values and code numbers. The table showing associations between symbols and code numbers (for instance,  FIG. 17 ) contains associations with respect to the left reel  5 , the center reel  6  and the right reel  7 . 
     As was described in the above text, in the symbol lottery process (S 59 ), the main CPU  42  executes the lottery program to sample random number values from the predetermined random number range (for instance 0 through 65535). The main CPU  42  then decides the code numbers based on the sampled random number values and the table containing associations between the random number values and the code numbers. The main CPU  42  decides the symbols to be positioned on the pay line L based on the code numbers and the table containing associations between the symbols and the code numbers. As a result, the main CPU  42  can decide a symbol combination constituted by three symbols positioned on the pay line L. 
     For instance, if the left reel  5  is the reel band shown in  FIG. 16  and random number value “1136” is sampled, the main CPU  42  decides for code number “08” based on the random number value “1136” and the table shown in  FIG. 17 . Then, the main CPU  42  decides the symbol positioned on the pay line L in the display window  15  to be the bar symbol  90 E based on the code number “08” and the table shown in  FIG. 16 . 
     The process using random number values in the symbol lottery process (S 59 ) is not limited to the process using random number values, a table containing associations between random number values and code numbers and a table containing associations between symbols and code numbers. 
     For instance, direct associations can be made between random number values to be sampled and symbols. The symbols to be stopped and displayed can also be decided using direct associations between the random number values to be sampled and winning combinations and the above tables. 
     The processes following the symbol lottery process (S 59 ) in the main game process program will now be described by referring to  FIG. 15 . 
     After the symbol lottery process (S 59 ) ends, the main CPU  42  executes a reel rotation control process (S 60 ). More specifically, the main CPU  42  drives motors M 1 , M 2  and M 3  through a motor driving circuit  52 . As a result, reels  5  through  7  start spinning. Thereafter, the main CPU  42  decides the effect pattern with respect to the unit game (the image display pattern onto the main liquid crystal panel  11 B and the sound output pattern from speaker  31 ) and transmits an effect signal to the sub-control board  72 , etc. Station  1  then starts effect execution using the decided effect pattern based on the control of the sub-control board  72 . When the predetermined time has lapsed, the main CPU  42  performs a reel stop operation. Specifically, the main CPU  42  stops reels  5  though  7  through the motor driving circuit  52 . At this time, the main CPU  42  stops reels  5  through  7  based on a code number decided in the symbol lottery process (S 59 ). As a result, the symbol combination decided at S 59  is repositioned on the pay line L. The main CPU  42  ends the reel rotation control process (S 60 ) following stopping of reels  5  through  7  and then shifts the process to S 61 . 
     After shifting to S 61 , the main CPU  42  judges whether the predetermined winning combination (refer to  FIG. 12 ) is established on the pay line L. More specifically, the main CPU  42  judges whether the symbol combination repositioned on the pay line L corresponds to the winning combination based on the code numbers, etc. of reels  5  through  7 . If the winning combination is established (S 61 : YES), the main CPU  42  shifts the process to the payout process (S 62 ). On the other hand, if the winning combination is not established (S 61 : NO), the main CPU  42  ends the main game process program. In this case, if a game starts following the next game, the main CPU  42  executes the processes following process S 51  once again. 
     At S 62 , the main CPU  42  executes a payout process. In this payout process (S 62 ), the main CPU  42  pays out an award (i.e., a payout) corresponding to the associated winning combination to the player. After ending the payout process (S 62 ), the main CPU  42  ends the main game process program. In this case, the main CPU  42  starts execution of the main game process program again, and executes the process at S 51 . 
     The processes S 55  through S 62  constitute a single unit game to be executed in the base game. 
     The award payout (payout) can be made in different ways. For instance, a payout method can be adopted in which coins corresponding to the number of credits (1 credit corresponds to 1 coin) are paid out when the CASHOUT button is held down. A payout method can also be adopted in which payment is made by tickets with a bar code. 
     Next, the processes (S 63  through S 66 ) regarding execution of the event game in the main game process program will be described. As was described in the above text, if an event game opening signal is received (S 54 : YES), the main CPU  42  shifts the process to S 63 . 
     At S 63 , the main CPU  42  judges whether the event game to be executed in the station  1  is the joint-style event game or not based on the event game start signal received. The overall control CPU  92  selects the type of the event game to be executed in the station  1  at the processes S 31  through S 38 . 
     Then, when the event game to be executed at the station  1  is judged as a joint-style event game (S 63 : YES), the main CPU  42  shifts the process to S 64 . Meanwhile, when the event game to be executed at the station  1  is judged as an independent-style event game (S 63 : NO), the main CPU  42  shifts the process to S 66 . 
     At S 64 , the main CPU  42  subtracts the bet amount corresponding to the entry fee collected at the above-mentioned S 34  due to the entry to the joint-style event game from the credit amount. After that, the main CPU  42  shifts the process to S 65 . 
     After shifting to S 65 , the main CPU  42  executes the joint-style event game execution process. This joint-style event game execution process (S 65 ) serves to execute a joint-style event game in the above station  1  in common with other stations  1  entering the event game. In this joint-style event game execution process (S 65 ), the main CPU  42  executes the joint-style event game execution process program. The joint-style event game execution process program will be described in detail by referring to the drawings. After ending the joint-style event game execution process (S 65 ), the main CPU  42  ends the main game process program. In this case as well, the main CPU  42  starts execution of the main game process program again, and executes the process at S 51 . 
     Meanwhile, at S 66  the main CPU  42  executes the independent-style event game execution process. This independent-style event game execution process (S 66 ) serves to execute an independent-style event game in the above station  1  in common with other stations entering the event game. In this independent-style event game execution process (S 66 ), the main CPU  42  executes the independent-style event game execution process program. The independent-style event game execution process program will be described in detail by referring to the drawings. After ending the independent-style event game execution process (S 66 ), the main CPU  42  ends the main game process program. In this case as well, the main CPU  42  starts execution of the main game process program again, and executes the process at S 51 . 
     Next, the joint-style event game execution process program will be described in detail by referring to the drawings.  FIG. 18  is a flow chart of the joint-style event game execution process program. 
     After shifting to the joint-style event game execution process (S 65 ), the main CPU  42  first executes the symbol lottery process (S 71 ). This symbol lottery process (S 71 ) is similar to the symbol lottery process (S 59 ) in the base game. Specifically, in the symbol lottery process (S 71 ), the main CPU  42  determines the symbol combination to be positioned on the pay line L in the unit event game. After ending the symbol lottery process (S 71 ), the main CPU  42  shifts the process to S 72 . 
     At S 72 , the main CPU  42  executes the reel rotation control process. This reel rotation control process (S 72 ) is similar to the reel rotation control process (S 60 ) in the base game. Accordingly, the symbols are scroll displayed by rotation of the reels in the display windows  15 ,  16  and  17  also in the unit event game (refer to  FIG. 9 ). When rotation of the reels is stopped, the symbols are repositioned based on the lottery results of the symbol lottery process (S 71 ) (refer to  FIG. 10 ). After repositioning the symbols based on the lottery results, the main CPU  42  shifts the process to S 73 . 
     After shifting to S 73 , the main CPU  42  executes the point addition process. This point addition process (S 73 ) serves to determine the game results of the unit event game and the event game. More specifically, the main CPU  42  calculates the event game points for the unit event game having as object three symbols positioned on the pay line L. As a result, the main CPU  42  judges the game results in the unit event game. The main CPU  42  accumulates and adds the event game points for the unit event game to the event game points obtained during the event game. As a result, the main CPU  42  judges the game results for the entire event game. 
     Here, the calculation of event game points in the unit event game will be described in detail by referring to the drawings. Upon calculating the event game points, the main CPU  42  references the lottery results of the symbol lottery process (S 71 ) and the event game point table shown in  FIG. 19 . As shown in  FIG. 19 , the event game point table contains event game points set for each type of symbol. For instance, the red seven symbol  90 B is associated with “50 points”. 
     Here, calculation of the event game points for the unit event game will be described taking as example the case that symbols are repositioned in the manner shown in  FIG. 10 . In the case shown in  FIG. 10 , “bar symbol  90 E”, “triple bar symbol  90 C” and “red seven symbol  90 B” are positioned on the pay line L. Accordingly, these three symbols become the object for calculating the event game points in the above unit event game. 
     Then, as shown in  FIG. 19 , “10 points” are associated to the “bar symbol  90 E” and “30 points” are associated to the “triple bar symbol  90 C”. Accordingly, the total number of event game points for the unit event game in this case is “90 points” which adds up “10 points”, “30 points” and “50 points”. 
     The event game points of the unit event game calculated as shown above are added to the present event game points as needed. Specifically, the player can obtain even higher event game points with the execution of the unit event game. After adding the event game points for the current unit event game to the present event game points, the main CPU  42  ends the point addition process (S 73 ). After ending the point addition process (S 73 ), the main CPU  42  shifts the process to S 74 . 
     The unit event game according to the present embodiment is realized by executing the processes from S 71  through S 73 . 
     After shifting to S 74 , the main CPU  42  judges whether the event game period has lapsed. More specifically, the main CPU  42  judges whether the event game end signal was received. As was described in the above text, the event game end signal is transmitted from the overall control CPU  92  if the event game period has lapsed (S 21 ). Accordingly, the main CPU  42  can judge whether the event game period has lapsed by judging whether the event game end signal was received. If the event game period has lapsed (S 74 : YES), the main CPU  42  shifts the process to S 75 . 
     On the other hand, the main CPU  42  returns the process to S 71  if the event game period has not lapsed yet (S 74 : NO). As a result, the player can execute a new unit event game. Specifically, the player can play the unit event game a plurality of times as long as it is within the event game period. 
     At S 75 , the main CPU  42  transmits the event game result information to the overall controller  91 . This event game result information shows the game results for the current event game (specifically, at the time of ending the event game). Specifically, the above event game result information shows the total value of the event game points obtained in the current event game. Then, the above event game result information is used as judging reference for identifying the station  1  that obtained the best event game results (S 23 ). After transmitting the event game result information to the overall controller  91 , the main CPU  42  shifts the process to S 76 . 
     After shifting to S 76 , the main CPU  42  judges whether the event game payout signal was received. The event game payout signal serves to instruct an event game payout with respect to the above station  1 . The above event game payout signal includes information showing the event game payout amount changed in the data renewal process (S 12 ). The event game payout signal is transmitted (S 24 ) from the overall controller  91  to the station  1  that obtained the best event game results based on the judgment results in the event game results judgment process (S 23 ). Specifically, if the above station  1  is the payout object station, the main CPU  42  receives the event game payout signal. 
     If the event game payout signal is received (S 76 : YES), the main CPU  42  shifts the process to S 77 . On the other hand, if no event game payout signal is received (S 76 : NO), the main CPU  42  ends the event game execution process program as is. In this case, the player of the above station  1  cannot obtain an event game payout in the current event game. 
     At S 77 , the main CPU  42  executes the event game payout process. In this event game payout process (S 77 ), the main CPU  42  awards an event game payout, based on the event game payout signal, to the player. As a result, the player that obtained the best event game results obtains an event game payout which is a progressive payout. After ending the event game payout process (S 77 ), the main CPU  42  ends the joint-style event game execution process program. 
     Next, the independent-style event game execution process program will be described in detail by referring to the drawings.  FIG. 20  is a flow chart of the event game execution process program. 
     After shifting to the independent-style event game execution process (S 66 ), the main CPU  42  first executes the symbol lottery process (S 81 ). This symbol lottery process (S 81 ) is similar to the symbol lottery process (S 59 ) in the base game. Specifically, in the symbol lottery process (S 81 ), the main CPU  42  determines the symbol combination to be positioned on the pay line L in the unit event game. After ending the symbol lottery process (S 81 ), the main CPU  42  shifts the process to S 82 . 
     At S 82 , the main CPU  42  executes the reel rotation control process. This reel rotation control process (S 82 ) is similar to the reel rotation control process (S 60 ) in the base game. Accordingly, the symbols are scroll displayed by rotation of the reels in the display windows  15 ,  16  and  17  even in the unit event game (refer to  FIG. 11 ). When rotation of the reels is stopped, the symbols are repositioned based on the lottery results of the symbol lottery process (S 81 ). After repositioning the symbols based on the lottery results, the main CPU  42  shifts the process to S 83 . 
     After shifting to S 83 , the main CPU  42  judges whether the predetermined winning combination (refer to  FIG. 12 ) is established on the pay line L. More specifically, the main CPU  42  judges whether the symbol combination repositioned on the pay line L corresponds to the winning combination based on the code numbers, etc. of reels  5  through  7 . If the winning combination is established (S 83 : YES), the main CPU  42  shifts the process to the payout process (S 84 ). On the other hand, if the winning combination is not established (S 83 : NO), the main CPU  42  shifts the process to S 85 . 
     At S 84 , the main CPU  42  executes a payout process. In this payout process (S 84 ), the main CPU  42  pays out an award (i.e., a payout) corresponding to the associated winning combination to the player. After ending the payout process (S 84 ), the main CPU  42  shifts the process to S 85 . 
     After shifting to S 85 , the main CPU  42  judges whether the event game period has lapsed. More specifically, the main CPU  42  judges whether the event game end signal was received. As was described in the above text, the event game end signal is transmitted from the overall control CPU  92  if the event game period has lapsed (S 21 ). Accordingly, the main CPU  42  can judge whether the event game period has lapsed by judging whether the event game end signal was received. If the event game period has lapsed (S 85 : YES), the main CPU  42  ends the independent-style event game execution program. 
     On the other hand, the main CPU  42  returns the process to S 81  if the event game period has not lapsed yet (S 85 : NO). As a result, the player can execute a free game repeatedly. Specifically, the player can play the free game a plurality of times as long as it is within the event game period. 
     As was described in the above text, in the gaming machine  100  according to the present embodiment, the five stations  1  execute the base game (S 55  through S 62 ) independently from each other. In this base game, each station  1  decides one game result (i.e., symbol combination) (S 59 ) and executes the base game. At this time, the above station  1  is not influenced in any way by the other stations  1 . 
     Here, the event game is executed in the above gaming machine  100  if the predetermined conditions (S 16  and S 17 ) are satisfied. The event game to be executed is selected among a plurality of event game types based on the operation rate of the gaming machine  100 . Specifically in the joint-style event game among the plurality of event game types, the players playing at a plurality (for instance, three or more) of stations  1  compete to obtain an event game payout. The event game payout is a progressive payout and is awarded to players that obtained the best game results in the event game. Meanwhile, specifically the joint-style event game among the plurality of event game types is a so-called free game. The player can be awarded a prize corresponding to the winning combination established at the free game executed during a predetermined time. 
     As a result, the above gaming machine  100  can execute the event game in which the content of the game is changed according to the operation rate at each of the plural stations. Thereby, the gaming machine  100  can provide the player with new interest to the game which differs from the base game. 
     The above gaming machine  100  continues to hold the used credit information until the data retention period has lapsed. The players can enjoy the profit (i.e., the payout change magnification ratio for the event game payout) based on their own used credit information, as long as they keep executing the base game. 
     If the bet operation (S 57  and S 58 ) for the base game is not executed during the data retention period (S 55 : YES), the used credit information for station  1  is initialized (S 14  and S 56 ). Accordingly, in case that the player stepped away from station  1 , the above gaming machine  100  can prevent third parties from being awarded profit (i.e., the payout change magnification ratio for the event game payout) with imbalance. 
     It is to be noted that the present invention is not limited to the above-described embodiment but, not to mention, it can be improved and modified in various ways within its scope and without departing from the subject matter thereof. 
     For instance, the present invention can also be realized as a gaming machine of the type shown in  FIG. 21 . 
     In the above description, in the gaming machine  100  according to the present embodiment, each station executes a base game and an event game having a slot game as base, however, the present invention is not limited to this aspect. Specifically, the present invention can be realized by executing a base game and an event game having a card game such as poker or black jack, etc. as base. 
     Further, in the above description, the gaming machine  100  according to the present embodiment executes a base game and an event game having the same type of game (slot game in the case of the present embodiment) as base, however, the invention is not limited to this aspect. Specifically, the base game and the event game may also have as base a game of a different type. For instance, a “slot game” can be adopted as a base game, and a “card game” can be adopted as an event game. In this case, the event game has to satisfy conditions such as “stations  1  that entered the game can advance the unit event game independently” and “the plurality of stations that entered the game compete for a common award”. 
     In the above embodiment, event game points based on three symbols positioned on the pay line L represent game results for the unit event game, however, the present invention is not limited to this aspect. For instance, nine symbols which can be visually recognized through the respective display windows  15 ,  16  and  17  may represent event game point calculation objects and may also represent game results of the unit event game. 
     In the present embodiment, a free game is executed as the independent-style event game, however, a selective bonus game can be executed other than a free game. 
     In the above embodiment, the event game to be executed is selected among a plurality of event game types based on the operation status of each station, however, the present invention is not limited to this aspect. For instance, the event game to be executed can be selected based on the credit number used or the payout rate of each station. 
     Upon initialization of the used credit information, the above station  1  can be constructed so as to give notice to the players on the execution period for used credit information initialization. For instance, a count down may also be displayed until used credit information initialization is executed (e.g., lapse of data retention period). 
     In the present embodiment, initialization of the used credit information is managed based on the players&#39; bet operation, however, the invention is not limited to this aspect. For instance, the player inherent ID card can be inserted in the above gaming machine  100 , and used credit information initialization can be executed based on the presence or absence of the above ID card. 
     The station  1  according to the present embodiment is a slot machine executing a slot game using three mechanical reels, however, it may also execute a slot game using five reels or nine reels, etc. A slot machine having video reels may also be used. 
     The present invention can be realized as a game method for executing the above processes. Further, the present invention can also be realized as a program for executing the above game method on a computer and a recording medium onto which this program is recorded. 
     Although the subject matter has been described in language specific to structural features and/or methodological acts, it is to be understood that the subject matter defined in the appended claims is not necessarily limited to the specific features or acts described above. Rather, the specific features and acts described above are disclosed as example forms of implementing the claims.