Patent Publication Number: US-8123612-B2

Title: Game system

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application claims priority of U.S. Provisional Application No. 61/034,653 filed on Mar. 7, 2008. The contents of this application are incorporated herein by reference in their entirety. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a game system made up of a plurality of slot machines. 
     2. Description of the Related Art 
     Slot machines known as a type of gaming machines are constituted so as to: start games by players inserting coins or the like into the gaming machine; rearrange columns of symbols in predetermined region of the gaming machine; and award a prize based on a combination of rearranged symbols. In addition, the above slot machines are generally constituted to judge whether or not a winning combination allowed to award a prize is established, based on whether or not a predetermined number of symbols of the same type (for example, “CHERRY” or “7”) are arranged along a preset payline. In the conventional slot machine, in the case where a predetermined number or more of symbols of the same type are arranged, it has been a common routine to award a prize based on the number of the aforementioned arranged symbols, regardless of the payout line. 
     Further, a bonus prize is set that is awarded in the case where a combination of symbols is rearranged in a specific order, in which a big prize, namely, so-called jackpot is awarded, thereby enhancing entertainability of the slot machine. The possibility of winning this jackpot, however, is kept low. Therefore, there is an aspect that players consider the jackpot as no more than an accidentally-winnable prize. 
     In a conventional slot machine, each of the slot machines executes a game independently, so that a plurality of players cannot enjoy as a group the game with the use of the plurality of slot machines. U.S. Pat. No. 7,056,215-B1, for example, discloses a game system that the plurality of game machines and a jackpot controller are connected via a network. In this system, the jackpot controller controls each of the game machines with respect to a trigger of a bonus game and a payout amount of the jackpot. However, the fact remains that the game itself is executed in each of the game machines. 
     U.S. Pat. No. 6,224,484 discloses a game system including the plurality of game machines and a progressive unit. In this system, a progressive bonus is paid out to one out of the plurality of game machines that won a prize during a main game. A game to determine the single game machine is executed in each of the game machines or the progressive unit but these game machines are not associated with each other, which does not fit the purpose that players enjoy a game as a group. 
     The present invention has been made in view of the above-described circumstance. It is an object of the present invention to provide a novel game system and a controlling method thereof that control a game so players are able to have expectations for the establishment of the jackpot to enhance entertainability and that execute a common game among the plurality of slot machines. 
     SUMMARY OF THE INVENTION 
     A first aspect of the present invention is a game system including a plurality of slot machines and a common game machine for executing a predetermined bonus game in connection with a game executed among the plurality of slot machines. The plurality of slot machines each has: an input device for accepting BET; a display device having a symbol display region for displaying plural types of symbols in a matrix form; a memory for cumulatively storing bonus points in the case where a specific symbol from among the plural types of symbols is rearranged in the symbol display region under a specific condition; a controller for executing processes for accepting the BET input through the input device, rearranging the plural types of symbols in the symbol display region of the display device, and cumulatively storing the bonus points in the memory. The common game machine has: a common display device provided in common to the plurality of slot machines, the common display device having a symbol display region for displaying plural types of symbols in a matrix form; a common memory for cumulatively storing a part of credit bet through the input device; and a common controller for selecting a column or row of a matrix displayed on the display device of each of the slot machines and rearranging, on the common display device, the symbol to be rearranged in the column or row by means of the common controller. The common controller selects the slot machine possessing the bonus points; executes the bonus game on the common display device; subtracts a predetermined number from the bonus points stored in the memory of each of the slot machines, every time the bonus game is executed; and awards a prize determined based on a cumulative value of the credit stored in the common memory, in the case where a predetermined condition is met during the bonus game. 
     According to the first aspect of the present invention, when the specific symbol is rearranged under the specific condition while the game is executed in each of the slot machines, bonus points are cumulated and stored in each of the slot machines and the right to participate in the bonus game the equal number of times to a cumulative value of the bonus points is endowed. Therefore, players can play the game with expectation that the jackpot might be awarded in the bonus game executed in the common game machine. 
     A second aspect of the present invention is a game system constituted as set fourth below. In the first aspect, the common controller rearranges in the symbol display region of the common display device the symbols to be rearranged in the selected row or column while the symbols are rearranged in the display device of each of the slot machines. 
     According to the second aspect of the present invention, the display device of each of the slot machines and the common display device proceed the game in sync with each other, which makes it more recognizable that the game rearranged in the common display device is a common game. 
     A third aspect of the present invention is a slot machine constituted as set forth below. In the first aspect, the common controller determines allotment of payout to each of the plurality of slot machines, based on a cumulative value of the bonus points stored in each of the memories. 
     According to the third aspect of the present invention, in the case where there are the plurality of slot machines that win the jackpot, the identical prizes may be awarded. However, the entertainability can be further enhanced by exercising control so as to award higher payout to the slot machine that won higher bonus points. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a perspective view schematically showing a common game machine and a plurality of slot machines configuring a game system; 
         FIG. 2  is a perspective view schematically showing an appearance of a slot machine according to the first embodiment; 
         FIG. 3A  is a block diagram depicting an internal construction of the slot machine shown in  FIG. 2 ; 
         FIG. 3B  is a block diagram depicting an internal construction of the common game machine shown in  FIG. 1 ; 
         FIG. 4A  is a view showing an exemplary symbol matrix displayed during the basic game in the slot machine shown in  FIG. 2 ; 
         FIG. 4B  is a view showing an exemplary symbol matrix displayed during the basic game in the slot machine shown in  FIG. 2 ; 
         FIG. 5A  is a view showing an exemplary symbol matrix displayed during the basic game in the slot machine shown in  FIG. 2 ; 
         FIG. 5B  is a view showing an exemplary symbol matrix displayed during the bonus game in the common game machine; 
         FIG. 6A  is a view showing an exemplary image displayed during the bonus game in the slot machine shown in  FIG. 2 ; 
         FIG. 6B  is a view showing an exemplary image displayed during the bonus game in the common game machine; 
         FIG. 7  is a view showing an exemplary image displayed during the bonus game in the common game machine; 
         FIG. 8  is a view showing an exemplary image displayed during the bonus game in the slot machine shown in  FIG. 2 ; 
         FIG. 9A  is a view showing an exemplary image displayed during the bonus game in the slot machine shown in  FIG. 2 ; 
         FIG. 9B  is a view showing an exemplary image displayed during the bonus game in the slot machine shown in  FIG. 2 ; 
         FIG. 10  is a flowchart showing a subroutine of a main process of the slot machine shown in  FIG. 2 ; 
         FIG. 11  is a flowchart showing a subroutine of a game execution process according to the slot machine shown in  FIG. 2 ; 
         FIG. 12  is a flowchart showing a subroutine of a basic game rearrangement process according to the slot machine shown in  FIG. 2 ; 
         FIG. 13  is a flowchart showing a subroutine of a bonus game execution process according to the common game machine; and 
         FIG. 14  is a flowchart showing a subroutine of a jackpot process of the common game machine. 
     
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     A game system according to the present invention will be explained in details with reference to the drawings. A plurality of slot machines  10   a  to  10   e  and a common game machine  75  configuring a game system  1  shown in  FIG. 1  according to the present invention are so-called video slot machines, each of which has an image display panel such as a liquid crystal display and executes a game by displaying images of various symbols on the image display panel. The plurality of slot machines  10   a  to  10   e  according to the present invention executes two gaming modes alternately. The two gaming modes include a basic game and a free game. The basic game is executed upon consumption of gaming values bet by players, namely, credit. The free game is executed without consuming the credit. On the other hand, the common game machine  75  is connected to the network in common with the respective slot machines so that players of the slot machines can execute the common game through the common game machine. 
     The common game machine  75  as shown in  FIG. 1  displays the symbol matrix with three rows and five columns in a display region. A common controller of the common game machine  75  designates one column of the symbol matrix with three rows and five columns displayed in the display region of each of the five slot machines  10   a  to  10   e . The common controller then rearranges the same symbols as those displayed in the above one column, in one column of a matrix with three rows and five columns displayed in the display device of the common game display  75 . Specifically, the symbol matrix with three rows and five columns displayed in the display device of the common game is made up of five single columns which are respectively collected from the symbol matrices of the five slot machines  10   a  to  10   e . In the case where the above common controller designates a row of the symbol matrix of each of slot machine, three of the five slot machines  10   a  to  10   e  are designated, and symbols to be rearranged in the single row of the symbol matrix of each of the designated slot machines are collected on the symbol matrix of the common game machine  75 . According to this game system, the players can enjoy respective games through the slot machines while enjoying the common game executed in the common game machine  75 . 
     According to the first embodiment of the present invention, during the basic games, that are executed independently in the respective slot machine  10   a  to  10   e , in the case where specific symbols are rearranged in a manner to satisfy a predetermined condition, the common controller awards a bonus point as a right to participate in a bonus game executed in the common game machine  75 , and then executes the bonus game in a state where the respective slot machines cumulate and hold bonus points. Further, the common controller awards the jackpot when the bonus symbol is arranged in the symbol matrix of the common game machine  75  under a predetermined condition during the bonus game. 
       FIG. 2  is a view schematically depicting an appearance of the slot machine according to the first embodiment. The gaming media used in the slot machine  10  include coins, bills, or electronic value information equivalent thereto. In the present invention, however, the gaming media are not limitative thereto in particular, and can include medals, tokens, electric money, and tickets, for example. The above tickets are not limitative in particular, and can include barcode-attached tickets or the like, as described later, for example. 
     The slot machine  10  is provided with a cabinet  11 , a top box  12  installed on an upper side of the cabinet  11 , and a main door  13  provided on a front surface of the cabinet  11 . 
     The lower image display panel  16  serving as a display device is provided in front of the main door  13 . The lower image display panel  16  is provided with a liquid crystal panel, which displays the cells of the symbol matrix  28  in three rows and five columns. A single symbol is arranged in each of the cells of the symbol matrix  28 , and the maximum of fifteen symbols can be displayed. 
     A credit amount display section  31  of the lower image display panel  16  displays credit corresponding to the number of inserted coins by way of an image. A payout amount display unit  32  displays by way of an image, a combination of rearranged symbols or the number of coins to be paid if the predetermined number of symbols are rearranged. 
     Provided on a lower side of the lower image display panel  16  at a center of the main door  13  is a control panel  20  on which a plurality of buttons  23  to  27  and  85  through which command regarding the process of the game is entered, a coin receiving slot  21  for receiving coins into the cabinet  11 , and bill validator  22  are disposed. 
     On the control panel  20 , a start button  23 , a change button  24 , a cashout button  25 , a 1-BET button  26 , a MAX-BET button  27 , and a side-BET button  85  are provided. The start button  23  is intended for entering a command for starting the game. The change button  24  is intended for use in asking an attendant of the gaming facility for change. The cashout button  25  is intended for entering a command for paying out the credited coins to a coin tray  18  through a coin payout exit  19 . 
     The 1-BET button  26  is intended for entering a command for betting credit corresponding to one coin. The MAX-BET button  27  is intended for entering a command for betting the maximum number (fifty in this embodiment) of coins that can be bet per game. The side-BET button  85  is used to place a bet on a sub game other than a game in which symbols are rearranged in the symbol matrix  28 . In this embodiment, for example, control can be performed to rearrange the symbol “CHANCE  70   a ” in the symbol matrix  28  when the predetermined credit is bet by the side-BET button  85 . A part of credit that has been bet through those input units are cumulatively stored in a memory region provided in a RAM  43  and are used as the reference to determine the amount of payout in the case where the jackpot is won during the bonus game. 
     The bill validator  22  validates whether or not a bill is legitimate and accepts a legitimate bill into the cabinet  11 . The bill validator  22  may be configured so that a barcode-attached ticket  39  described later is readable thereby. Provided on a lower front surface of the main door  13 , that is, at a lower part of the control panel  20 , is a berry glass  34  on which characters of the slot machine  10  and the like are depicted. 
     On a front surface of the top box  12 , an upper image display panel  33  is provided. The upper image display panel  33  has a liquid crystal panel, which displays images for introducing the game contents or explaining game rules, for example. 
     Also, on the top box  12 , a speaker  29  and a lamp  30  are provided. On a lower side of the upper image display panel  33 , a ticket printer  35 , a card reader  36 , a data display unit  37 , and a key pad  38  are provided. The ticket printer  35  prints on the ticket, a barcode having encoded thereon data such as the credit amount, the date and time, and the identification number of the slot machine  10 , and outputs the printed ticket as the barcode-attached ticket  39 . The player can play the game on another slot machine with the barcode attached ticket  39  by causing this slot machine to read the barcode attached ticket  39 . Alternatively, the player can exchange the barcode-attached ticket  39  with the bills or the like at a predetermined place (at a cashier inside a casino, for example) of the gaming facility. 
     The card reader  36  reads data from and writes data into a smart card. The smart card is to be owned by the player, which stores data for identifying the player or data regarding the log of games executed by the player, for example. The smart card may store data corresponding to coins, bills, or credit. As an alternative of a smart card, a magnetic stripe card may be employed. The data display  37  is made up of a fluorescent display and the like, and displays the data read by the card reader  36  or the data input by the player through the key pad  38 , for example. The key pad  38  inputs data and commands regarding the ticket issuance or the like. 
       FIG. 3A  is a block diagram depicting the internal construction of the slot machine shown in  FIG. 2 . A gaming board  50  includes: a CPU (Central Processing Unit)  51 , a ROM (Read Only Memory)  55  and a boot ROM  52  interconnected by an internal bus; a card slot  53 S corresponding to a memory card  53 ; and an IC socket  54 S corresponding to a GAL (Generic Array Logic)  54 . 
     The memory card  53  contains therein a nonvolatile memory and stores game programs. The game programs include a symbol selection program. The aforementioned symbol selection program is intended for determining the symbols to be rearranged in the symbol matrix SM. The aforementioned symbol selection program includes symbol weighing data respectively corresponding to plural types of payout ratios (80%, 84%, and 88%, for example). The symbol weighting data is indicative of the correspondence relationship between the respective symbols and one or more random numeric values which come under a predetermined numerical range (0 to 255). The payout ratio is determined according to the payout-ratio setting data output from the GAL  54 . The symbols to be rearranged in the symbol matrix  28  are determined depending upon the symbol weighing data corresponding to this payout ratio. Further, the game programs include table data indicating the correspondence relationship between each of the symbols and a payout. 
     Also, the card slot  53 S is configured to allow the memory card  53  to be inserted thereinto or ejected therefrom, and is connected to a motherboard  40  through IDE pass. Accordingly, the memory card  53  can be ejected from the card slot  53 S, other game programs and other game system programs can then be written into the memory card  53 , and further, the memory card  53  can be inserted into the card slot  53 S, thereby allowing the player to change the types and contents of games executed in the slot machine  10 . The game program includes data concerning a game progress. Furthermore, the game program includes image data or sound data to be output during the game. The image data include, for example, image data indicative of the symbol matrix  28 . 
     The GAL  54  is a type of a PLD having a fixed OR array structure. The GAL  54  includes plural input ports and plural output ports. Where predetermined data is input to the input port, the GAL  54  outputs data corresponding to the aforementioned data from the output port. The data output from this output port is equivalent to the aforementioned payout-ratio setting data. Further, the IC socket  54 S is configured to allow the GAL  54  to be attached thereto and detached therefrom, and is connected to the motherboard  40  by a PCI bus. Accordingly, the GAL can be replaced with the replacement GAL  54  to change the payout-ratio setting data. 
     The CPU  51 , the ROM  55 , and the boot ROM  52  interconnected by the internal bus are connected to the motherboard  40  by the PCI bus. The PCI bus serves to transmit signals between the motherboard  40  and the gaming board  50  and supply power from the motherboard  40  to the gaming board  50 . 
     The motherboard  40  is constructed using a general-purpose motherboard commercially available (a printed circuit board on which essential parts of a personal computer are mounted) and includes: a main CPU (Central Processing Unit)  41 , a ROM (Read Only Memory)  42 ; a RAM (Random Access Memory)  43 ; and a communication interface  44 . 
     The ROM  42  stores thereon a program such as BIOS (Basic Input/Output System) executed by a main CPU  41 , and permanent data. When the BIOS is executed by the main CPU  41 , processing of initializing predetermined peripheral devices is carried out and processing of capturing game programs and game system programs stored in the memory card  53  through the gaming board  50  is started. In the present invention, the contents of the ROM  42  may be rewritable or not. 
     The RAM  43  stores data and a program used when the main CPU  41  is activated. The RAM  43  can also store game programs. The RAM  43  further stores data concerning the credit amount, the number of coin-in or coin-out for one game, and the like. In embodiments of the present invention, the RAM  43  stores bonus points cumulatively. 
     Both a main body PCB (Printed Circuit Board)  60  and a door PCB  80  are connected to the motherboard  40  by USB. A power supply unit  45  is also connected to the motherboard  40 . 
     Connected to the main body PCB  60  and the door PCB  80  are: equipment and devices which generate input signals to be input to the main CPU  41 ; and equipment and devices of which operations are controlled by a control signal output from the main CPU  41 . The main CPU  41  executes a game program stored in the RAM  43  based on an input signal having been input to the main CPU  41  and performs a predetermined computational process, thereby storing results thereof in the RAM  43  or transmitting a control signal to each of equipment and devices as a control process therefor. 
     A lamp  30 , a hopper  66 , a coin detecting section  67 , a graphic board  68 , a speaker  29 , a touch panel  69 , the bill validator  22 , the ticket printer  35 , the card reader  36 , a key switch  38 S, and the data display unit  37  are connected to the main body PCB  60 . The lamp  30  is lit up in a predetermined pattern based on a control signal output from the main CPU  41 . 
     The hopper  66  is installed in the cabinet  11  and pays out a predetermined number of coins from the coin payout exit  19  to the coin tray  18  based on a control signal output from the main CPU  41 . The coin detecting section  67  is installed inside the coin payout exit  19  and outputs an input signal to the main CPU  41  upon detecting that a predetermined number of coins have been paid out from the coin payout exit  19 . 
     The graphic board  68  controls, based on a control signal output from the main CPU  41 , images to be displayed on the upper image display panel  33  and the lower image display panel  16 . The credit amount stored in the RAM  43  is displayed on a credit amount display section  31  (see  FIG. 2 ) of the lower image display panel  16 . The number of coins to be paid out is displayed at a payout amount display section  31  (see  FIG. 2 ) of the lower image display panel  16 . The graphic board  68  is equipped with a VDP (Video Display Processor) which generates image data based on a control signal output from the main CPU  41  and a video RAM which temporarily stores image data generated by the VDP, and the like. The image data used in generating image data with VDP is contained in the game program read from the memory card  53  and stored in the RAM  43 . 
     The bill validator  22  validates whether or not a bill is legitimate and accepts a legitimate bill into the cabinet  11 . Upon accepting a legitimate bill, the bill validator  22  outputs an input signal to the main CPU  41  based on the amount of the bill. The main CPU  41  stores in the RAM  43  the credit amount corresponding to the amount of bills transmitted by the input signal. 
     Based on a control signal output from the main CPU  41 , the ticket printer  35  prints on a ticket a barcode having encoded thereon data such as the credit amount, data and time, and the identification number of the slot machine  10  stored in the RAM  43 . Further, this printer outputs the printed ticket as a barcode-attached ticket  39 . The card reader  36  transmits to the main CPU  41  the data read from the smart card and writes the read data onto the smart card, based on a control signal from the main CPU  41 . The key switch  38 S is provided on the key pad  38 , and outputs a predetermined input signal to the main CPU  41  when the player operates the key pad  38 . The data display  37 , based on a control signal output from the main CPU  41 , displays the data read by the card reader  36  and the data input by the player through the key pad  38 . 
     The control panel  20 , a reverter  21 S, a coin counter  21 C, and a cold cathode tube  81  are connected to the door PCB  80 . The control panel  20  is provided with: a start switch  23 S corresponding to the start button  23 ; a change switch  24 S corresponding to the change button  24 ; a cashout switch  25 S corresponding to a cashout button  25 ; a 1-BET switch  26 S corresponding to a 1-BET button  26 ; a MAX-BET switch  27 S corresponding to the MAX-BET button  27 ; and a side-BET switch  90 S corresponding to the side-BET switch  85 . When the player operates the buttons  23  to  27  and  85 , the corresponding switches  23 S to  27 S and  90 S output input-signals to the main CPU  41 , respectively. 
     The coin counter  21 C is provided inside the coin receiving slot  21 , and validates whether or not a legitimate coin is inserted into the coin receiving slot  21 . Those other than the legitimate coins are discharged from the coin payout exit  19 . The coin counter  21 C outputs an input signal to the main CPU  41  when a legitimate coin is detected. 
     The reverter  21 S operates based on a control signal output from the main CPU  41  and distributes coins recognized as being legitimate by the coin counter  21 C into a cash box (not shown in the drawings) or the hopper  66  which is arranged in the slot machine  10 . In other words, when the hopper  66  is filled with coins, legitimate coins are distributed by the reverter  21 S into the cash box. On the other hand, when the hopper  66  is not filled with coins, legitimate coins are distributed into the hopper  66 . The cold cathode tube  81  functions as a backlight installed on rear face side of each of the lower image display panel  16  and the upper image display panel  33 , and is lit up based on a control signal output from the main CPU  41 . 
       FIG. 3B  is a block diagram depicting an internal construction of the common game machine  75  shown in  FIG. 1 . The common game device  75  includes a communication I/F  154  for conducting communication between the respective slot machines  10   a  to  10   e  and the main CPU  41 , a RAM  153 , a ROM  152 , a CPU  151  functioning as a common controller, and a graphic board  168  for displaying images by controlling a display device  116 . 
     The ROM  42  stores thereon a program such as BIOS (Basic Input/Output System) executed by the CPU  151 , and permanent data. When the BIOS is executed by the CPU  151 , processing of initializing predetermined peripheral devices is carried out and the RAM  153  reads a control program of the common game machine  75  and a game system program. The RAM  43  stores data related to a game, such as a cumulative value of credit possessed by each of the slot machines or bonus points. The graphic board  168  controls images displayed in the display device  116  based on a control signal output from the main CPU  151 . 
       FIGS. 4A to 9B  are views each showing an exemplary image displayed on an image display panel  16  of the slot machine  10  shown in  FIG. 2  according to the first embodiment.  FIGS. 4A and 4B  are views each showing an exemplary image displayed during a basic game in the slot machine shown in  FIG. 2 . 
     As shown in  FIG. 4A , the lower image display panel  16  is made up of a display region  92 , an information display section  93 , the effect image display section  94 , and the like. The symbol matrix  28  is displayed in the display region  92 . On both sides of the symbol matrix  28 , the icons indicative of the number of coins that have been bet are arranged, and control is performed to blink the icon corresponding to the bet amount. The information display section  93  is arranged upwardly of the display region  92  and is made up of a credit amount display section  93   a , a BET amount display section  93   b , a character information display section  93   c , a PAID amount display section  93   d , and a charge display section  93   e.    
     The number of coins currently credited is displayed at the credit amount display section  93   a  while the number of coins bet on one game is displayed at the BET amount display section  93   b . The character information indicative of a current status of the game is displayed at the character information display section  93   c . The characters of “PLAYNOW” are displayed during the play of the game, whereas the characters of “GAMEOVER” are displayed during the intervals between the plays of the game. The number of coins that have been paid out in one game is displayed at the PAID amount display section  93   d , whereas a conversion value of the credit amount based on a predetermined amount of money is displayed at the charge display section  93   e.    
     The effect image display section  94  displays effect images according to a type of the slot game. In other words, the effect image display section  94  displays different effect images between the basic and free games. 
     Any of symbols, “main character  121 ”, “sub character  122 ”, “office building  123 ”, “gold bullion  124 ”, “car  125 ”, “stock certificate  126 ”, “jet  127 ”, “villa  128 ”, and “CHANCE  70   a ” are rearranged in the elements of the symbol matrix displayed on the lower image display panel  16 . A payout is determined based on the number of these symbols rearranged in the symbol matrix. 
       FIG. 4A  is a view showing a case where the symbols, “main character  121 ”, “sub character  122 ”, “office building  123 ”, “gold bullion  124 ”, “car  125 ”, “stock certificate  126 ”, “jet  127 ”, “villa  128 ”, and “CHANCE  70   a ” are rearranged in the symbol matrix  28  during the basic game. The single symbol “CHANCE  70   a ” is rearranged, which does not meet the condition to win the bonus point, so that the icon “BONUS  70   d ” is not displayed in the effect image display section  94 . On the other hands, the two symbols “main character  121 ” are displayed, each of which serves a trigger to switch the basic game to the free game. The condition to start the free game is met when three or more symbols “main character  121 ” are rearranged. This condition is not met in this case, thereby not starting the free game. 
       FIG. 4B  also shows an exemplary symbol matrix displayed during the basic game, in which the symbols, “main character  121 ”, “sub character  122 ”, “office building  123 ”, “gold bullion  124 ”, “car  125 ”, “stock certificate  126 ”, “jet  127 ”, “villa  128 ”, and “CHANCE  70   a ” are rearranged in the symbol matrix  28  in three rows and five columns. In this exemplary case, the three symbols “CHANCE  70   a ” are rearranged. One bonus point is awarded when the three symbols “CHANCE  70   a ” are rearranged, and the icon “BONUS  70   d ” is displayed in an effect image display region  94  right above the symbol matrix (see  FIGS. 4A and 4B ). The bonus points are cumulatively stored in a storage area of the RAM  43 , and a right is provided, that is to execute the bonus game by the equal number of times to the cumulative value. 
       FIG. 5A  is a view showing an exemplary symbol rearrangement in the symbol matrix  28  during the basic game, related to determination of start of the bonus game. Herein, the three symbols “CHANCE  70   a ” are rearranged in the symbol matrix  28 . As a result, one more icon “BONUS  70   d ” is added. In  FIG. 5A , the five icons “BONUS  70   d ” are displayed in the effect image display region  94 , indicating that five bonus points are won. Therefore, the bonus game can subsequently be executed five times. 
     The CPU  151  as the common controller of the common game machine  75  starts the bonus game when any one of the slot machines  10   a  to  10   e  cumulates five bonus points (see  FIG. 13 ). The slot machine shown in  FIG. 5A  wins five points, so that the CPU  151  executes the bonus game with the common game machine  75 . 
       FIG. 5B  is a view showing an exemplary image displayed in the display device of the common game machine  75  during the bonus game. In the case where start of the bonus game is determined, a display image  71   a  in  FIG. 5B  is displayed in the display device  116  of the common game machine  75  while a scrolling screen is displayed in the matrix display region of the display device  116 . The display image  71  a indicates that the bonus game is started after twenty seconds. 
       FIG. 6A  is a view showing an exemplary image displayed in the lower image display panel  16  of the slot machine  10  during the bonus game. When the bonus game is started, the slot machines possessing the bonus points execute individually a symbol rearrangement game according to an instruction from the common controller CPU  151  of the common game machine  75 . When a display image  71   a  in  FIG. 5B  is displayed in the display device  116  of the common game machine  75 , players of the slot machines that participate in the bonus game are required to push the start button  23  in twenty seconds. When the start button  23  is pushed, in each of the slot machines, the main CPU  41  rearranges the symbols in the symbol matrix  28 . In the case shown in  FIG. 6A , the CPU  151  of the common game machine  75  designates a column  172  in  FIG. 6A  and rearranges in a column  100   e  of the symbol matrix displayed in the display device  116  of the common game machine  75 , the symbols, “car  125 ”, “sub character  122 ”, and “villa  128 ” that are rearranged in the column  172  of the symbol matrix  28  shown in  FIG. 6A . Selection of a column by the common controller CPU  151  is not fixed but determined at random just before rearrangement of symbols in each of the symbol matrices. 
       FIG. 6B  shows a view showing an exemplary image rearranged in the symbol matrix of the common game machine  75  during the bonus game. As described above, each of the symbols “car  125 ”, “sub character  122 ”, and “villa  128 ”, that are rearranged in the column  172  of the symbol matrix  28  of the slot machine displaying a screen shown in  FIG. 6A , is rearranged in the column  100   e . The symbols that are rearranged in columns  100   a  to  100   d  are respectively the same as those rearranged in the symbol matrices of the different slot machines. In this case, three symbols “stock certificate  126 ” and three symbols “villa  128 ” are rearranged in the symbol matrix rearranged in the display device  116  of the common game machine  75 , and a corresponding payout is awarded as an outcome of the common game to each of the slot machines that participate in the bonus game. In the symbol matrix  28  of the slot machine shown in  FIG. 6A , no prizes are established, so that a payout is not awarded as an outcome of the game executed in the individual slot machine but awarded as an outcome of the common game. 
       FIG. 7  also shows an exemplary image rearranged in the symbol matrix of the common game machine  75  during the bonus game. The symbol matrix displays three bonus symbols “sub character  122 ”, which meets the condition for establishment of the bonus prize, so that a jackpot is awarded. In this case, the jackpot is awarded to all of the slot machines that participate in this time&#39;s bonus game. The payout can be equally allocated to the respective slot machines but may be allocated in accordance with a cumulative number of bonus points possessed by each of the slot machines. 
       FIGS. 8 and 9  are views each showing an exemplary image displayed in the lower image display panel  16  of the slot machine  10  that wins the jackpot during the bonus game. The number of coins that are paid out in association with the jackpot is determined according to a cumulative value of credit stored in a predetermined region in the RAM  153  of the common game machine. The generally adopted method is that the jackpot is classified into three, i.e., “MIN”, “MAJOR”, and “MEGA” according to the cumulative value. In the case of a small cumulative value, the number of paid-out coins is small and the jackpot called “MIN” is awarded. On the other hand, in the case of both a cumulative value and the number of paid-out coins turn out large, the jackpot called “MAJOR” or “MEGA” is awarded. A screen shown in  FIGS. 8 and 9  is displayed in order to indicate the payout amount according to the jackpot. 
     In  FIG. 8 , two cars are displayed in the display region  92  in the lower image display panel  16  of the slot machine  10  and a car race is started. Next, in  FIG. 9A , a screen “WIN” is displayed in the display region  92 . In the case of displaying this screen, the jackpot classified into “MAJOR” or “MEGA” is awarded. On the other hand, in the case of displaying a screen “LOSE” shown in  FIG. 9B , the jackpot classified into “MIN” is awarded. The screen displayed in this manner enhances entertainability. 
     Next, a process executed in the slot machine  10  according to the first embodiment, will be described in detail with reference to the drawings. The main CPU  41  controls the progress of a game by reading out of the RAM  43  and executing the game program. 
       FIG. 10  is a flowchart showing a subroutine of a main process. In the main process, first, when a power switch is turned on (that is, when power is supplied), a motherboard  40  and a gaming board  50  are activated respectively, so that the CPU  51  executes an initial setting process (step S 101 ). In this initial setting process, the main CPU  41  executes the BIOS stored in the ROM  42 , decompresses, in the RAM  43 , compressed data included in the BIOS, executes the BIOS decompressed in the RAM  43 , and performs diagnosis and initialization of each of the peripheral devices. The main CPU  41  writes game programs or the like from the memory card  53  into the RAM  43 , and retrieves data for setting a payout ratio and country-identification information. The main CPU  41  also performs an authentication process for each program during execution of the initial setting process. 
     Next, the main CPU  41  performs a game execution process described later with reference to  FIG. 8  (step S 102 ). In this game execution process, the main CPU  41  sequentially reads and executes the game programs or the like from the RAM  43 . By performing this game execution process, the slot machine according to the first embodiment  10  executes the game. The game execution process is repeatedly performed while power is supplied to the slot machine  10 . 
       FIG. 11  is a flowchart showing a subroutine of the game execution process invoked and performed at step S 102  of the subroutine shown in  FIG. 10 . First, the main CPU  41  judges whether a coin has been bet or not (step S 201 ). Specifically, the main CPU  41  judges whether or an input signal has been received. The input signal is output from the 1-BET switch  26 S at the time of operation of the 1-BET button  26  or output from the MAX-BET switch  27 S at the time of operation of the MAX-BET button  27 . The main CPU  41  controls the current step to return to the process at step S 201  upon judging that no coin has been bet (step S 201 : NO). 
     Next, the main CPU  41  subtracts the number of bet coins from the credit amount stored in the RAM  43  (step S 202 ) upon judging that a coin has been bet (step S 201 : YES). Where the number of bet coins is larger than the credit amount stored in the RAM  43 , the main CPU  41  controls the current step to return to step S 201  without performing the process for subtracting the number of bet coins from the credit number stored in the RAM  43 . Where the number of bet coins exceeds the upper limit ( 50  coins in this embodiment) of coins that can be bet in one game, the main CPU  41  controls the step to return to step  201  without performing the process for subtracting the number of bet coins from the credit number stored in the RAM  43 . 
     The main CPU  41  judges whether or not the start button  23  has been set to ON (step S 203 ). Specifically, the main CPU  41  judges whether or not an input signal output from the start switch  23 S at the time of pushing of the start button  23  has been received. The main CPU  41  controls the step to return to step  201  upon judging that the start button  23  has not been set to ON (step S 203 : NO). Where the start button  23  has not been set to ON (for example, where an instruction has been input to terminate the game without setting the start button  23  to ON), the main CPU  41  cancels acceptance of a subtraction result at step S 202 . 
     On the other hand, the main CPU  41  performs a symbol rearrangement process (step S 204 ) upon judging that the start button  23  has been set to ON (step S 203 : YES). Specifically, the CPU  41  executes the program stored in the RAM  43  and determines the symbols to be rearranged in the symbol matrix. The symbols are selected from among the symbols, “main character  121 ”, “sub character  122 ”, “office building  123 ”, “gold bullion  124 ”, “car  125 ”, “stock certificate  126 ”, “jet  127 ”, “villa  128 ”, “CHANCE  70   a ”, and “blank”. This determination is based on the symbol weighting data and random numeric values sampled by sampling the random numeric values in a numerical range which comes under a predetermined range of random numeric values. The CPU  41  then rearranges the symbols in the symbol matrix. 
     Next, the main CPU  41  judges whether a prize has been established or not (step S 205 ). Specifically, the main CPU  41  judges whether or not a combination of symbols rearranged in the symbol matrix  28  results in a winning combination allowed to award any of payouts. Herein, the prize is established on condition that the three or more symbols of the same type are rearranged in the symbol matrix  28 . 
     Next, upon judging that the prize is established (step S 205 : YES), the main CPU  41  performs a predetermined coin-payout process (step S 206 ). In the coin-payout process, the main CPU  41  transmits the control signal to the hopper  66  to pay out the predetermined amount of coins. The CPU  41  may control the process to add the credit corresponding to the coins to be paid out to the credit amount stored in the RAM  43 . 
     Next, the CPU  41  judges whether a free game trigger condition has been met or not (step S 207 ) when judging that the prize is not established (step S 205 : NO) or after executing the payout process at step S 206 . Specifically, the main CPU  41  executes the program stored in the RAM  43  to sample the random numeric values in a numerical range which comes under a predetermined range of random numeric values, thereby judging whether or not the symbol “main character  121 ” is rearranged based on the sampled random numeric values. The main CPU  41  then counts the number of the rearranged symbols “main character  121 ” and judges that the free game trigger condition is met when the three or more symbols “main character  121 ” are rearranged. The main CPU  41  performs the free game execution process (step S 208 ) when judging that the free game trigger condition is met (step S 207 : YES). In this free game execution process, the main CPU  41  reads and executes game programs or the like out of the RAM  43  in sequence, thereby executing the free game execution process. On the other hand, the main CPU  41  terminates the game execution process when judging that the free game trigger condition is not met at step S 207  (step S 207 : NO) or when executing the process at step S 208 . 
       FIG. 12  is a flowchart showing a subroutine of a symbol rearrangement process which is invoked and executed at step S 204  of the subroutine shown in  FIG. 11 . First, the main CPU  41  displays the symbols in a scrolling manner (step S 301 ). Specifically, the main CPU  41  executes the program stored in the RAM  43  to perform virtual display of an effect image that is virtually recognized as if the symbols are scrolled at high speed in a downward direction of a column of the symbol matrix. 
     The main CPU  41  then judges whether the side-BET button  85  has been set to ON or not (step S 302 ). Specifically, the main CPU  41  judges whether or not the input signal has been received, the signal being output from the side-BET switch  90 S when the side-BET button  85  is pressed. Upon judging that the side-BET button  85  has been set to ON (step S 302 : YES), the main CPU 41  executes a process at step S 303 . Upon judging that the side-BET button  85  has not been set to ON (step S 302 : NO), the main CPU  41  executes a process at step S 304 . 
     At step S 303 , the main CPU  41  selects a group of symbols containing the symbol “CHANCE  70   a ” from among a plurality of groups of symbols stored in the RAM  43 . On the other hand, the CPU  41  selects the group of symbols not containing the symbol “CHANCE  70   a ” from among the plurality of groups of symbols stored in the RAM  43 . In this manner, control is performed to rearrange the symbol “CHANCE  70   a ” in the symbol matrix  28  only when the side-BET has been placed. 
     The main CPU  41  then rearranges the symbols selected at step S 303  or step S 304 , in the symbol matrix (step S 305 ). Specifically, the main CPU  41  executes the program stored in the RAM  43  to compare a numeric value determined based on each symbol weighting data to a random numeric value generated correspondingly to each cell of the symbol matrix  28 , thereby determining the symbol to be arranged in each cell of the symbol matrix, from among the group of symbols selected at step S 303  or S 304 . The main CPU  41  then rearranges the determined symbols. 
     Next, the main CPU  41  makes a judgment as to whether or not the symbol “CHANCE  70   a ” is contained in the symbols rearranged in the symbol matrix at step S 305 . In the case where the symbol “CHANCE  70   a ” is not contained, the main CPU  41  terminates the symbol rearrangement process (step S 306 : NO). Where the symbol “CHANCE  70   a ” is contained in the symbols rearranged in the symbol matrix  28 , the main CPU  41  counts the number of symbols “CHANCE  70   a ”. Upon judging that three or more symbols “CHANCE” are contained (step S 306 : YES), the main CPU  41  causes the effect image display section  94  to display an effect image that one more icon “BONUS” is added (step S 307 ). 
     The main CPU  41  then invokes a cumulative value of bonus points stored in the RAM  43 , the value being equal to the number of icons “BONUS  70   d ” having been displayed by the time of the previous symbol rearrangement process. The main CPU  41  adds one to the value and then stores it again in the RAM  43  (step S 308 ). The main CPU  41  terminates the symbol rearrangement process throughout the above described process. 
       FIG. 13  is a flowchart showing a bonus game execution process executed in the common game machine  75 . First, the CPU  151  as the common controller of the common game machine  75  receives information on a cumulative number of bonus points stored in a predetermined region in the RAM  43 , from the main CPU  41  of each of the slot machines, and then judges whether to execute the bonus game (step S 401 ). Specifically, the CPU  141  judges whether or not there is a slot machine in which a cumulative number of bonus points reaches five. The CPU  151  terminates the subroutine upon judging that a cumulative number of each of the slot machine is smaller than five (step S 401 : NO). On the other hand, upon judging that there is a slot machine possessing a cumulative value equal to five (step S 401 : YES), the CPU  151  shifts the current step to the process for executing the bonus game. 
     The CPU  151  receives the information on a cumulative number of bonus points stored in the predetermined region in the RAM  43 , from the main CPU  41  of each of the slot machines, and then selects a slot machine possessing a cumulative value of bonus points not equal to zero (step S 402 ). 
     Next, the CPU  151  displays an effect image for start of the bonus game in the display device  116  (step S 403 : see  FIG. 5B ). 
     After setting the start button  23  to ON in each of the slot machines, the CPU  151  designates a column displayed in the symbol matrix of the display device  116  and receives information on symbols to be rearranged in the designated column from the CPU  41  of each of the slot machines (step S 404 ). At this step, in the case where the number of slot machines that are allowed to participate in the bonus game is smaller than five and the symbol matrix with three rows and five columns cannot be configured, the CPU  151  designates the symbol matrix  28  of each of the slot machines that do not participate in the bonus game, and receives information on symbols to be rearranged in the designated column from each of the CPUs  41  of those slot machines. 
     Upon receipt of information on symbols from the main CPU  41  of each of the slot machines, the CPU  151  rearranges the symbols in the symbol matrix of the display device  116  (step S 405 ). At this step, the CPU  151  provides an instruction regarding a timing of rearrangement to the CPU  41  of each of the slot machines from which the CPU  151  received the information on symbols. The CPU  151  is then synchronized with each of the slot machines. 
     The CPU  151  then judges whether or not a bonus prize has been established (step S 406 ). Specifically, the main CPU  41  judges whether or not three or more bonus symbols “sub character  122 ” are rearranged in the symbol matrix  28  (see  FIG. 7 ). Upon judging that the bonus prize has been established (step S 406 : YES), the main CPU  41  performs a jackpot process (step S 408 ). Specifically, the CPU  151  receives from the main CPU  41  of each of the slot machines  10   a  to  10   e , information on a cumulative value of credit cumulatively stored in the memory region set in the RAM  43  of each of those slot machines  10   a  to  10   e , and then performs a payout process of coins, the number of which is determined based on a sum total of the received cumulative values (step S 506 : see  FIG. 14 ). On the other hand, upon judging that the bonus prize has not been established (step S 406 : NO), the CPU  151  shifts the current step to the process for judging as to establishment of another prize (step S 407 ). 
     The main CPU  151  then judges whether or not the condition for awarding the prize has been established (step S 407 ). Specifically, the CPU  151  judges whether or not three or more symbols are rearranged in the symbol matrix  28  of the display device  116  (see  FIG. 6B ). Upon judging that the prize has been established (step S 407 : YES), the CPU  151  then instructs the main CPU  41  of each of the slot machines to pay out the corresponding number of coins to each prize (step S 409 ). 
     On the other hand, upon judging that the prize has not been established (step S 407 : NO) and executing a process at step S 409 , the CPU  151  instructs the main CPU  41  of each of the slot machines to subtract one from a cumulative value of bonus points stored in the RAM  43  (step S 410 ). 
     Next, the CPU  151  receives information on a cumulative value of bonus points stored in the RAM  43  from the main CPU  41  of each of the slot machines  10   a  to  10   e , and judges whether or not there is a slot machine that possesses a cumulative value of bonus points not equal to zero, the value being stored in the RAM 43 . Upon judging that there is a slot machine that possesses a cumulative value not equal to zero (step S 411 : YES), the CPU  151  controls the current step to return to the process at step  402 . On the other hand, upon judging that all slot machines possess a cumulative value of bonus points equal to zero (step S 411 : NO), the main CPU  151  terminates a subroutine. 
       FIG. 14  is a flowchart of the jackpot process invoked and executed at step S 408  of the subroutine shown in  FIG. 13 . First, the CPU  151  instructs the main CPU  41  of each pf the slot machines participating in the bonus game to display in the display region  92  of the lower image display panel  16  an effect image (see  FIG. 8 ) indicating that the bonus prize has been established and the jackpot is to be paid out (step S 501 ). 
     Next, the CPU  151  receives from the main CPU  41  of each of the slot machines  10   a  to  10   e , information on a cumulative value of credit stored in the RAM  43 . The CPU  151  then sums the above cumulative vales and stores the sum total in a predetermined region in the RAM  153  of the common game machine  75 . The CPU  151  then judges the amount of the jackpot, based on the sum total value (step S 502 ). Specifically, the CPU  151  determines into which of “MIN”, “MAJOR”, and “MEGA” the jackpot is classified, the jackpot being paid out based on a cumulative value of credit. 
     The CPU  151  judges whether or not the jackpot to be paid is classified into “MIN” (step S 503 ). In the case of the jackpot being classified into “MIN”, the CPU  151  instructs the main CPU  41  of each of the slot machines participating in the bonus game to display in the display region  92  of the lower image display panel  16  an effect image of “LOSE” (see  FIG. 9B ) indicating that the jackpot of “MIN” is to be paid out (step S 504 ). On the other hand, where the jackpot is classified into either one of “MAJOR” and “MEGA”, the CPU  151  instructs the main CPU  41  to display in the display region  92  of the lower image display panel  16  an effect image of “WIN” (see  FIG. 9A ) indicating that the jackpot of “MAJOR” or “MEGA” is to be paid out (step S 505 ). 
     Next, the CPU  151  instructs the main CPU  41  of each of the slot machines participating in the bonus game to pay out the jackpot (step S 506 ). In this case, the jackpot is awarded to all of the slot machines participating in the bonus game. The payout can be equally allocated to the respective slot machines but may be allocated in accordance with a cumulative number of bonus points possessed by each of the slot machines. In the case where the coins are deposited, the main CPU  41  performs a process for adding the number of paid-out coins to the credit amount stored in the RAM  43 . In the case where the coins are paid out, the main CPU  41  pays out the predetermined number of coins by transmitting the control signal to the hopper  66 . 
     In the foregoing, while the embodiments of the present invention have been described, these embodiments merely present specific examples. An appropriate design change can be made for the specific configuration of each means or the like. Also, the effects described in the embodiments of the present invention are only listing the most preferable effects arising from the present invention, and the effects of the present invention are not limited to those described in the embodiments of the present invention.