Title:
SLOT MACHINE EXECUTING FREE GAME ACCORDING TO GAME OUTCOME OF SUB GAME
Kind Code:
A1


Abstract:
A slot machine executes a sub game during a base game, and executes a free game in response to a game outcome of the executed sub game. Specifically, the slot machine is configured to execute the sub game different from the base game during the base game when symbols arranged on a main liquid crystal panel during the base game forms a combination in which three “CHANCE” symbols are arranged on a payline. Moreover, the slot machine is configured to execute the free game by switching from the base game to the free game when the player satisfies a winning condition a predetermined number of times or more in the sub game.



Inventors:
Okada, Kazuo (Tokyo, JP)
Application Number:
12/025317
Publication Date:
08/21/2008
Filing Date:
02/04/2008
Assignee:
Aruze Corporation (Koto-ku, JP)
Primary Class:
International Classes:
A63F9/24
View Patent Images:



Primary Examiner:
PANDYA, SUNIT
Attorney, Agent or Firm:
OBLON, SPIVAK, MCCLELLAND MAIER & NEUSTADT, P.C. (1940 DUKE STREET, ALEXANDRIA, VA, 22314, US)
Claims:
What is claimed is:

1. A slot machine comprising: a display adapted to have a plurality of symbols arranged on the display; a bet receiving button configured to receive a bet operation; and a controller configured to execute a base game and a free game by switching these games under predetermined conditions, the base game being designed to start in response to a consumption of gaming values equivalent to a bet amount received by the bet receiving button, and to award a prize when the plurality of symbols arranged on the display forms a predetermined combination, the free game being designed to start without requiring any gaming value to be consumed, and to award a prize when the plurality of symbols arranged on the display forms a predetermined combination, wherein the controller is configured to execute a sub game different from the base game during the base game, and to switch a game mode from the base game to the free game in response to a game outcome of the sub game.

2. A slot machine comprising: a display adapted to have a plurality of symbols arranged on the display; a bet receiving button configured to receive a bet operation; and a controller configured to execute a base game and a free game by switching these games under predetermined conditions, the base game being designed to start in response to a consumption of gaming values equivalent to a bet amount received by the bet receiving button, and to award a prize when the plurality of symbols arranged on the display forms a predetermined combination, the free game being designed to start without requiring any gaming value to be consumed, and to award a prize when the plurality of symbols arranged on the display forms a predetermined combination, wherein the controller is configured to execute a sub game different from the base game during the base game; to determine whether a player satisfies a winning condition a predetermined number of times of more in the sub game; and to switch a game mode from the base game to the free game when the controller determines that the player satisfies the winning condition the predetermined number times or more.

3. A slot machine comprising: a display adapted to have a plurality of symbols arranged on the display; a bet receiving button configured to receive a bet operation; and a controller configured to execute a base game and a free game by switching these games under predetermined conditions, the base game being designed to start in response to a consumption of gaming values equivalent to a bet amount received by the bet receiving button, and to award a prize when the plurality of symbols arranged on the display forms a predetermined combination, the free game being designed to start without requiring any gaming value to be consumed, and to award a prize when the plurality of symbols arranged on the display forms a predetermined combination, wherein the controller is configured to execute a sub game different from the base game when a predetermined combination including a particular symbol is arranged on the display during the base game; to determine whether or not a player satisfies a winning condition for the sub game a predetermined number of times of more; and to switch a game mode from the base game to the free game when the controller determines that the player satisfies the winning condition for the sub game the predetermined number of times or more.

4. The slot machine according to claim 1, wherein the controller is configured to execute the sub game different form the base game when a combination including a particular symbol is arranged on the display during the base game.

5. The slot machine according to claim 1, wherein when a predetermined condition is satisfied during the base game, the controller is configured to select one sub game among a plurality of types of sub games and executes the selected sub game.

6. The slot machine according to claim 1, wherein the sub game includes a plurality of types of sub games, and the plurality of types of sub games have different challenge levels from each other, the challenge levels imposed on a player to satisfy winning conditions of the respective sub games.

7. The slot machine according to claim 1, wherein the controller is configured to determine the number of times of the free game to be executed subsequently to the sub game, on the basis of a game outcome of the sub game, and to execute the free game the determined number of times.

Description:

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a slot machine that executes a sub game during a base game and executes a free game in response to a game outcome of the executed sub game.

2. Description of the Related Art

A conventional slot machine that is one type of gaming machine is configured: to start a game when gaming values such as coins are inserted into the gaming machine; to display columns of symbols in a scrolling manner on a predetermined area of the gaming machine, then to stop scrolling and display the symbols after a predetermined time has elapsed, and to award a prize based on the combination of the stopped symbols. Moreover, whether or not a combination for awarding a prize is established is generally determined according to whether or not a predetermined number of symbols of one kind (for example, “CHERRY” or “7”) are arranged on a preset payline. In addition, heretofore, a prize has been also awarded based on a combination not related to a payline. For example, U.S. Pat. No. 6,334,612 discloses a slot machine that displays a total of 15 symbols of 3×5 by using video reels or mechanical reels. In this slot machine, the reels are rotated once a game starts, and symbols arranged in a vertical direction in each column start scrolling in synchronization with the rotation of the reels. Then, when the reels stop rotating after a predetermined time has elapsed, three stopped symbols are displayed in each column. If the displayed symbols stop in a combination including a predetermined number of symbols or more of one kind, a prize is awarded.

Here, a plenty of conventional slot machines are known, each of which executes two kinds of games, that is, a base game and a free game. The base game is a game executed with a consumption of gaming values (coins, credits or the like) equivalent to a bet amount. On the other hand, the free game is a game executed without requiring gaming values equivalent to a bet amount to be consumed. The game is switched from the base game to the free game in a case where a predetermined condition is satisfied, such as a case where a predetermined symbol is stopped and displayed. Then, the game is switched from the free game to the base game in a case where a predetermined condition is satisfied, such as a case where the free game has been already executed a predetermined number of times.

Here, a player desires the slot machine to execute the free game that provides a higher probability of obtaining a large number of gaming values. In the conventional slot machine, therefore, the player has been obliged to be kept waiting for a start of the free game by repeating the base game, and accordingly, to accept such a monotonous play style.

The present invention provides a slot machine providing enhanced entertainment by variously changing a condition for starting a free game in such a way that a sub game different from a base game is executed during the base game, and that the free game is then started in response to a game outcome of the sub game.

SUMMARY OF THE INVENTION

A slot machine of the first aspect of the present invention includes a display adapted to have multiple symbols arranged on the display, a bet receiving button configured to receive a bet operation, and a controller configured to execute a base game and a free game by switching these games under predetermined conditions. Here, the base game is designed to start in response to a consumption of gaming values equivalent to a bet amount received by the bet receiving button, and to award a prize when the plurality of symbols arranged on the display forms a predetermined combination, while the free game is designed to start without consuming any gaming value, and to award a prize when the plurality of symbols arranged on the display forms a predetermined combination. In addition, the controller is configured to execute a sub game that is different from the base game, in the base game, and switch the game mode from the base game to the free game in response to a game outcome of the sub game.

The slot machine of the first aspect of the present invention having the aforementioned configuration starts the free game in response to the game outcome of the sub game that is different from the base game. For this reason, the condition for starting the free game does not have to be limitative only to a game outcome of the base game, and thus, the condition for starting the free game can be variously changed. In addition, a player is allowed to play the sub game in addition to the base game, thus avoiding monotony of the game. This enables the player to continue playing the game for a long time. Thus, the entertainment of the game is enhanced.

A slot machine of the second aspect of the present invention includes a display adapted to have a plurality of symbols arranged on the display, a bet receiving button configured to receive a bet operation, and a controller configured to execute a base game and a free game by switching these games under predetermined conditions. Here, the base game is designed to start in response to a consumption of gaming values equivalent to a bet amount received by the bet receiving button, and to award a prize when the plurality of symbols arranged on the display forms a predetermined combination, while the free game is designed to start without requiring any gaming value to be consumed, and to award a prize when the plurality of symbols arranged on the display forms a predetermined combination. The controller is configured to execute a sub game that is different from the base game during the base game, to determine whether a player satisfies a winning condition a predetermined number of times of more in the sub game, and to switch the game mode from the base game to the free game when the controller determines that the player satisfies the winning condition the predetermined number of times or more.

The slot machine of the second aspect having the aforementioned configuration starts the free game when the controller determines that a player satisfies the winning condition a predetermined number of times or more in the sub game. Accordingly, with the progress of the sub game, the slot machine of the second aspect can promote player's expectations for the start of the free game. Hence, the entertainment of the game is enhanced.

A slot machine of the third aspect of the present invention includes a display adapted to have a plurality of symbols arranged on the display, a bet receiving button configured to receive a bet operation, and a controller configured to execute a base game and a free game by switching these games under predetermined conditions. The base game is designed to start in response to a consumption of gaming values equivalent to a bet amount received by the bet receiving button, and to award a prize when the plurality of symbols arranged on the display forms a predetermined combination, while the free games are designed to start without requiring any gaming value to be consumed, and to award a prize when the plurality of symbols arranged on the display forms a predetermined combination. The controller is configured to execute a sub game different from the base game when a predetermined combination including a particular symbol is arranged on the display during the base game, to determine whether or not a player satisfies a winning condition for the sub game a predetermined number of times or more, and then, to switch the game mode from the base game to the free game when the controller determines that the player satisfies the winning condition the predetermined number of times or more.

The third slot machine of the third aspect having the aforementioned configuration executes the sub game when the combination including the particular symbol is arranged on the display in the base game, and then, starts the free game when the controller determines that the player satisfies the winning condition the predetermined number of times or more in the thus executed sub game. This promotes player's expectations for an event where the particular symbol is arranged in the base game, and also promotes player's expectations for the start of the free game with the progress of the sub game. Thus, the entertainment of the game is enhanced.

A slot machine of the fourth aspect of the present invention includes the controller of the slot machine of the first aspect. The controller of the slot machine of the fourth aspect is configured to execute the sub game different from the base game when a combination including a particular symbol is arranged on the display in the base game.

Since the slot machine of the fourth aspect having the aforementioned configuration executes the sub game when the combination including the particular symbol is arranged on the display in the base game, player's expectations for an event where the particular symbol is arranged in the base game are enhanced.

A slot machine of the fifth aspect of the present invention includes the controller of the first slot machine. The controller of the fifth slot machine is configured to select one sub game among multiple types of sub games when a predetermined condition is satisfied during the base game, and then to switch the game mode from the base game to the free game in response to a game outcome of the selected sub game.

The slot machine of the fifth aspect having the aforementioned configuration has the multiple types of sub games, and the executed sub game is changed for every session of the sub game, thus avoiding monotony of the game. In addition, the condition for switching to the free game can also be changed for every session of the sub game, so that the entertainment of the game is enhanced.

A slot machine of the first aspect of the present invention has the sub game of the first slot machine including multiple types of sub games. The multiple types of sub games have different challenge levels from each other, the challenge levels imposed on a player to satisfy winning conditions of the respective sub games.

In the slot machine of the sixth aspect having the aforementioned configuration, since the multiple types of sub games employ the different challenge levels to be imposed on the player to satisfy the respective winning conditions, and thereby, the player feels a different level of expectations, depending on the type of the executed sub game, for switching to the free game. Hence, the slot machine of the sixth aspect provides the player with such a different level of expectations depending on the type of the selected sub game, thereby enhancing the entertainment of the game. Furthermore, the slot machine of the sixth aspect is capable of providing the game that lets even a player with a poor gaming technique enjoy playing sufficiently and prevents a player with a good gaming technique from getting bored.

A slot machine of the seventh aspect of the present invention includes the controller of the first slot machine of the first aspect. The controller of the slot machine of the seventh aspect is configured to determine the number of times of the free game to be executed subsequently to the sub game, on the basis of a game outcome of the sub game.

Since the slot machine of the seventh aspect having the aforementioned configuration determines the number of times of the free game to be executed subsequently to the sub game, on the basis of a game outcome of the sub game, player's expectations for acquiring a large amount of gaming values in the subsequently-executed free game changes according to the game outcome of the executed sub game. Thereby, the entertainment of the game is enhanced.

Since the slot machine according to the present invention starts the free game in response to the game outcome of the sub game different from the base game, the condition for starting the free game does not have to be limitative only to the game outcome of the base game, but can be variously changed. Moreover, the player is allowed to play the sub game in addition to the base game. As a result, the monotony of the game is avoided, and this enables the player to continue playing the game for a long time. Thus, the entertainment of the game is enhanced.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a diagram showing a feature of a slot machine according to a present embodiment.

FIG. 2 is a perspective view showing an external appearance of the slot machine according to this embodiment.

FIG. 3 is a schematic diagram showing symbol columns drawn on reel bands of the respective reels.

FIG. 4 is a block diagram showing an internal configuration of the slot machine according to this embodiment.

FIG. 5 is a block diagram showing an internal configuration especially of a sub-control board of the slot machine according to this embodiment.

FIG. 6 is a diagram showing a game screen displayed on a main liquid crystal panel during an execution of the base game.

FIG. 7 is a diagram showing a game screen displayed on the main liquid crystal panel during the execution of the base game.

FIG. 8 is a payout table showing winning combinations and payout amounts for the respective winning conditions in a case where the base game and a free game are executed by using the reels.

FIG. 9 is a diagram showing a game screen displayed on the main liquid crystal panel during an execution of the sub game.

FIG. 10 is a diagram showing a game screen displayed on the main liquid crystal panel during the execution of the sub game.

FIG. 11 is a diagram showing a game screen displayed on the main liquid crystal panel during the execution of the sub game.

FIG. 12 is a diagram showing a list of sub games executed in the slot machine according to this embodiment.

FIG. 13 is a flowchart of a main control processing program in the slot machine according to this embodiment.

FIG. 14 is a flowchart of a main game processing program in the slot machine according to this embodiment.

FIG. 15 is a flowchart of a sub game processing program in the slot machine according to this embodiment.

DESCRIPTION OF THE PREFERRED EMBODIMENT

Hereinafter, an exemplary embodiment of a slot machine according to the present invention will be described in detail with referring to the drawings. Here, a slot machine according to the following embodiment is a so-called hybrid-type slot machine being provided with a known transparent liquid crystal panel arranged in front of multiple rotatably-supported mechanical reels and executing games by making the liquid crystal panel transparent to display the images of various symbols drawn on the outer peripheral surfaces of the mechanical reels.

In addition, a feature of the slot machine according to the present invention is that the slot machine not only executes a base game and a free game but also a sub game. More precisely, the base game is one which a player plays by consuming gaming values equivalent to a bet amount, the free game is one which the player plays without consuming any gaming value, and the sub game is different from the base game and is executed during the base game. Moreover, another feature of the slot machine is that the base game is switched to the free game not in response to a game outcome of the base game, but in response to a game outcome of the sub game.

For example, FIG. 1 shows a case where the present invention is applied to a slot machine including three columns of reels 5 to 7. When the base game is started in the slot machine, each of the reels 5 to 7 starts rotating, and scrolling symbol columns are displayed. Then, after a predetermined time has elapsed, the reels 5 to 7 stop rotating one by one from the left-hand side, symbols of up to 9 are displayed in a symbol display area as shown in FIG. 1(1). Here, when three “CHANCE” symbols are stopped on a payline L altogether, the sub game is started during the base game as shown in FIG. 1(2). Incidentally, there are multiple types of sub games, and one of the sub games to be executed is selected every time before a new session of the sub game is started. In FIG. 1, a description is given as to a case where a subgame of picking a winning card among from multiple shuffled cards is selected. In the sub game, multiple cards including a “winning card” and “losing cards” are displayed on a main liquid crystal panel 11B, and the cards are shuffled. Thereafter, if a player picks the “wining card” three times in the sub game as shown in FIG. 1(3), which is a winning condition for the player, the sub game is terminated and the game mode is switched from the base game to the free game. Thus, the free game is started as shown in FIG. 1(4). The number of times in a case where the free game is to be executed at this time changes depending on the number of picked cards needed until the condition that the “winning card” is picked three times is satisfied. If the condition is satisfied by three trials, four trials, and five trials, the player is allowed to play the free game 20, 10 and 5 times, respectively. On the other hand, if the player picks the “losing card” three times during the sub game, which is a losing condition for the player, the sub game is terminated and the base game is continuously executed.

First of all, a schematic configuration of a slot machine 1 according to this embodiment will be described based on FIG. 2. FIG. 2 is a perspective view of an external appearance of the slot machine 1 according to this embodiment. The slot machine 1 according to this embodiment is an upright type slot machine installed in a game arcade such as a casino, and includes a cabinet 2, a main door 3 provided in the front surface of the cabinet 2, and a topper announcement effect device 4 arranged above the cabinet 2.

The cabinet 2 is intended for housing electric or mechanical components for executing predetermined game modes. Three of a left reel 5, a middle reel 6 and a right reel 7 are rotatably provided to the inside of the cabinet 2. A symbol column (see FIG. 3) consisting of 22 symbols is drawn on the outer peripheral surface of each of the reels 5 to 7. In addition, the main liquid crystal panel 11B provided to the main door 3 is arranged in front of the reels 5 to 7.

The main door 3 includes, as a display unit 10 for displaying information on the game, an upper display unit 10A, a variable display unit 10B on the middle side, and a lower display unit 10C. The upper display unit 10A is provided with an upper liquid crystal panel 11A arranged above the variable display unit 10B. Thus, for example, an effect image, a presentation of the game content, and an explanation of game rules or the like are displayed on the upper liquid crystal panel 11A. The lower display unit 10C includes a plastic panel 11C arranged below the variable display unit 10B and having an image printed thereon. Then, this plastic panel 11C is illuminated with a backlight.

Moreover, the variable display unit 10B for displaying the situation of executing the game includes the main liquid crystal panel 11B constituted of a known transparent liquid crystal panel fixed to the main door 3. Here, three display windows 15, 16 and 17 are formed in the main liquid crystal panel 11B, and allow the side behind the main liquid crystal panel 11B to be viewed. The symbols drawn on the reels 5 to 7 are made visible by making the display windows 15, 16 and 17 transparent. In addition, one payline L horizontally crossing a symbol display area corresponding to all the reels 5 to 7 is displayed on the main liquid crystal panel 11B in the variable display unit 10B. The payline L is used to define a combination of symbols. If a combination of symbols stopped and displayed on the payline L is a predetermined combination, a payout amount corresponding to the combination and a bet credit amount (bet amount) is provided. Incidentally, five reels may be employed instead of the three reels, and the number of displayed symbols is not limitative to 9.

Moreover, the front surface of the main liquid crystal panel 11B is provided with a touch panel 18, and a player can input various instructions by operating the touch panel 18. In the slot machine 1 according to this embodiment, the touch panel 18 is used by the player to select one of choices (for example, cards) displayed in the sub game which will be described later.

Furthermore, a payout amount display portion 19 and a credit amount display potion 20 are provided on the right lower side of the variable display unit 10B. The payout amount display portion 19 displays, as a payout amount, a payout amount provided in the base game if a combination of symbols stopped and displayed on the payline L is a predetermined combination or a cumulative payout amount obtained in the free game. The credit amount display potion 20 displays a credit amount currently owned by the player.

An operation table 25 extending forward is provided between the variable display unit 10B and the lower display unit 10C in the front surface of the cabinet 2. On the operation table 25, various operation buttons 26 such as a BET button, a correct button, a start button and a CASHOUT button are arranged as an operation area for making instructions for an execution of the game. In addition, a coin insertion slot 27 for inserting coins into the cabinet 2 and a bill insertion slot 28 for inserting bills in the cabinet 2 are provided on the operation table 25.

Incidentally, for the slot machine 1 according to this embodiment, coins, bills and equivalent electronic value information (credit) are used as the game gaming values. However, the game gaming values usable in the present invention are not limitative thereto, but also include medals, tokens, e-money and tickets, for example.

A coin tray 29 receiving coins provided by a hopper is provided to the lowest portion of the cabinet 2. In addition, a lighting unit 30 is disposed around the cabinet 2 of the slot machine 1, and lights up in a predetermined lighting manner in the case of winning or during the free game. A speaker 31 outputting sounds is also provided at each side of the cabinet 2.

Moreover, the slot machine 1 includes the topper announcement effect device 4 above the cabinet 2. This topper announcement effect device 4 is in a rectangular board shape, and is disposed substantially in parallel with the upper liquid crystal panel 11A of the upper display unit 10A.

Subsequently, based on FIG. 3, a description will be furnished as to the symbols drawn on the left reel 5, the middle reel 6 and the right reel 7, and rearranged while scrolling in the respective display windows 15 to 17 of the main liquid crystal panel 11B through during executions of the base game and the free game. FIG. 3 is a schematic diagram showing symbol columns drawn on the reel belts of the left reel 5, the middle reel 6 and the right reel 7.

22 symbols are drawn on each of the reel belts of the reels 5 to 7. Each of the symbol columns is constituted of a configuration of symbols “CHANCE”, “BLUE7”, “BELL”, “APPLE”, “CHERRY”, “STRAWBERRY”, “PLUM” and “ORANGE”. Then, predetermined kinds of symbols are arranged in a predetermined order in each of the symbol columns.

In this regard, when three symbols of each of “BLUE7”, “BELL”, “APPLE”, “CHERRY”, “STRAWBERRY”, “PLUM” and “ORANGE” are rearranged on the payline L on the main liquid crystal panel 11B, a player is provided with a predetermined payout amount (see FIG. 8). In addition, when even one or two symbols of each of “CHERRY” and “ORANGE” are rearranged on the payline L on the main liquid crystal panel 11B, a player is provided with a predetermined payout amount predetermined corresponding to the number of symbols (see FIG. 8).

Moreover, when three symbols “CHANCE” are rearranged on the payline L on the main liquid crystal panel 11B, a predetermined payout is provided to the player and the sub game is executed in parallel with the base game. Incidentally, symbol numbers are assigned in descending order to the respective symbols constituting each of the symbol columns shown in FIG. 3.

Next, an internal configuration of the aforementioned slot machine 1 will be described with referring to FIGS. 4 and 5. FIG. 4 is a block diagram showing an entire internal configuration of the slot machine 1. As shown in FIG. 4, the slot machine 1 is constituted of multiple components including, as a main component, a main control board 71 having a controller 41 for executing a control program (FIGS. 13 to 15), which will be described later. The main control board 71 includes the controller 41, a random number generation circuit 45, a sampling circuit 46, a clock pulse generation circuit 47, a frequency divider 48, a lighting effect drive circuit 61, a hopper drive circuit 63, a payout completion signal circuit 65 and a display-unit drive circuit 67.

The controller 41 includes a main CPU 42, a RAM 43 and a ROM 44. The main CPU 42 operates in accordance with programs stored in the ROM 44 and controls the operations of the entire slot machine 1 by inputting and outputting signals from and to the other components through an I/O port 49. The RAM 43 stores therein data and programs used in the operations of the main CPU 42. For instance, in the RAM 43, random number values sampled by the sampling circuit 46, which will be described later, are temporarily stored after the game has started, and the code numbers of the respective reels 5 to 7 and the symbol numbers are also stored. The ROM 44 stores therein the programs executed by the main CPU 42 and permanent data.

In particular, the programs stored in the ROM 44 include a game program and a game system program (hereinafter, referred to as a game program and the like). Moreover, the game program includes first to third lottery programs described below.

The first lottery program is a program for determining one of the code numbers for each of the reels 5 to 7, and the determined code number corresponds to a symbol to be rearranged on the payline L in the main liquid crystal panel 11B. This lottery program includes symbol weighting data corresponding to multiple kinds of payout rates (for example, 80%, 84% and 88%). The symbol weighting data is data indicative of correspondence between each of the code numbers of the three reels 5 to 7, and one or more random numbers within a predetermined range of numeric values (0 to 255). In other words, a single code number is associated with one or more random numbers, each of which corresponds to one of the payout rates. After a predetermined random number is extracted by lottery, a symbol eventually specified from the extracted random number is rearranged on the payline L in the main liquid crystal panel 11B. Note that the lottery program for determining symbols to be arranged may use weighting data in which a predetermined range of numeric values is associated with a prize awarded to a player. In this case, first, a prize to be awarded to a player is determined by lottery in accordance with the lottery program. Then, a combination of symbols satisfying the determined prize is selected by the main CPU 42.

The second lottery program is a program for determining one of the sub games to be executed when the sub game is about to be executed. This lottery program includes a sub game selection table corresponding to each of multiple types of sub games (for example, a “shuffle card game”, a “spot the difference”, a “horse racing game”, a “memory”, a “quiz” and the like). The sub game selection table is data indicative of correspondence between each of the sub games and one or more random numbers within a predetermine range of numeric values (0 to 255). In short, by extracting one of the random numbers by lottery, the subgame specified from the random number is determined as the subgame to be executed.

The third lottery program is a program for determining various kinds of parameters needed to execute each type of the sub games. For example, when the “shuffle card game” or “memory” is to be executed as the sub game, kinds of cards to be arranged on the main liquid crystal panel 11B are determined. Instead, when the “spot the difference” is to be executed as the sub game, two images of characters and scenery to be displayed on the main liquid crystal panel 11B are determined as a target for “spot the difference”. Alternatively, when the “horse racing game” is to be executed as the sub game, a horse to win is determined. Moreover, when the “quiz” is to be executed as the sub game, questions to be given and choices of answers are determined.

The random number generation circuit 45 operates in accordance with instructions from the main CPU 42, and generates a predetermined range of random numbers. The sampling circuit 46 extracts a predetermined one of the random numbers generated by the random number generation circuit 45 in accordance with an instruction from the main CPU 42 and inputs the extracted random number to the main CPU 42. The clock pulse generation circuit 47 generates reference clocks for operating the main CPU 42, and the frequency divider 48 inputs, to the main CPU 42, the signal obtained by dividing the frequency of the reference clocks into a predetermined frequency.

In addition, a reel drive unit 50 is connected to the main control board 71. This reel drive unit 50 includes a reel position detecting circuit 51 for detecting the position of each of the reels 5 to 7, and a motor drive circuit 52 for inputting drive signals to motors M1, M2 and M3 for rotating the respective reels 5 to 7. The motors M1, M2 and M3 operate in response to an input of the drive signals from the motor drive circuit 52, rotate the respective reels 5 to 7, and then, stop the reels 5 to 7 at desired positions.

Moreover, a touch panel 18 is connected to the main control board 71, and is disposed in front of the main liquid crystal panel 11B. This touch panel 18 is capable of identifying a coordinate position of a part touched by a player, and that of determining, by using the identified coordinate position information, where the player touches and in which direction the touched part moves. Then, a signal corresponding to the determination is inputted to the main CPU 42 through the I/O port 49.

The operation buttons 26 including the start button, the correct button, the BET button and the like, for making an instruction for an execution of the game, are connected to the main control board 71. Then, a signal responsive to a press of one of the buttons is inputted to the main CPU 42 through the I/O port 49.

The lighting effect drive circuit 61 outputs effect signals for causing the foregoing lighting unit 30 and topper announcement effect device 4 to produce lighting effects. The topper announcement effect device 4 is serially connected to a lighting effect drive circuit 61 through the lighting unit 30.

A hopper drive circuit 63 drives a hopper 64 under control of the main CPU 42. Thereby, the hopper 64 pays out coins to the coin tray 29 by performing an operation for paying out coins. A payout completion signal circuit 65 receives value data on the number of coins from a coin detection unit 66 that is connected to the payout completion signal circuit 65. When the number of paid-out coins reaches a set number of coins, the payout completion signal circuit 65 inputs, to the main CPU 42, a signal notifying the main CPU 42 of the completion of payout of coins. The coin detection unit 66 counts the number of coins provided by the hopper 64, and inputs the value data on the counted number of coins to the payout completion signal circuit 65. The display-unit drive circuit 67 controls display operations of various display portions such as the payout amount display portion 19 and the credit amount display potion 20.

Moreover, a sub-control board 72 is connected to the main control board 71. As shown in FIG. 5, the sub-control board 72 receives commands from the main control board 71, and controls the displays of the upper liquid crystal panel 11A of the upper display unit 10A and the main liquid crystal panel 11B of the variable display unit 10B, as well as the sound output from the speaker 31. This sub-control board 72 is configured on a circuit board that is different from the circuit board constituting the main control board 71. The sub-control board 72 includes a microcomputer (hereinafter, referred to as a “sub-microcomputer”) 73, as a main component, and also includes 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 is employed as an amplifier, and the image control circuit 81 operates as a display control unit for the upper liquid crystal panel 11A and the main liquid crystal panel 11B.

The sub-micro computer 73 includes a sub CPU 74 that performs control operations in accordance with control commands transmitted from the main control board 71, as well as a program ROM 75 and a work RAM 76 as storages, and I/O ports 77 and 80. The sub-control board 72 is not provided with a clock pulse generation circuit, a frequency divider, a random number generation circuit or a sampling circuit, but is configured to execute random number sampling on an operation program of the sub CPU 74. The program ROM 75 stores therein a control program executed by the sub CPU 74. The work RAM 76 is configured as a temporal memory used when the sub CPU 74 executes the control program.

The image control circuit 81 includes 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. In accordance with an image control program stored in the image control program ROM 84, the image control CPU 82 determines images to be displayed on the upper liquid crystal panel 11A and the main liquid crystal panel 11B.

The image control program ROM 84 stores therein the image control program for the displays on the upper liquid crystal panel 11A and the main liquid crystal panel 11B, and various selection tables. The image control work RAM 83 is configured as a temporal memory used when the image control CPU 82 executes the image control program. The image control IC 88 forms images corresponding to the content determined by the image control CPU 82, and outputs the images to the upper liquid crystal panel 11A and the main liquid crystal panel 11B.

The image ROM 86 stores therein dot data for forming images. The video RAM 87 operates as a temporal memory used when the image control IC 88 forms the images.

Next, a description will be given as to the base game, the free game and the sub game executed in the slot machine 1 having the aforementioned configuration. First of all, the base game is explained. The base game is a slot game that causes the reels 5 to 7 to rearrange a particular combination of symbols on the payline L in the main liquid crystal panel 11B. Specifically, when the player sets the bet amount by operating the operation buttons 26 and depresses the start button, the reels 5 to 7 start rotating. As a result, as shown in FIG. 6, the symbol columns drawn on the reel belts of the respective reels 5 to 7 are displayed through the display windows 15 to 17 in the transparent state, while scrolling from the upper side to the lower side. Then, after a predetermined time has elapsed, the reels 5 to 7 automatically stop on a one-by-one basis in a predetermined order. With this stop, as shown in FIG. 7, part of the symbol columns drawn on the reel belts of the respective reels 5 to 7 (three symbols for each reel, that is, nine symbols 91 in total) are rearranged and displayed on the main liquid crystal panel 11B through the display windows 15 to 17 in the transparent state. Here, as to the base game, various kinds of winning combinations each are predetermined as one of combinations of symbols that are rearranged on the main liquid crystal panel 11B. Thus, when three symbols rearranged on the payline L in the main liquid crystal panel 11B form a combination corresponding to one of the winning combinations, the player is provided with a credit amount obtained by multiplying a payout amount corresponding to the formed winning combination by the bet amount.

On the other hand, the free game executed in the slot machine 1 is a game executed by switching from the base game if a player satisfies a winning condition three times in the sub game, which will be described later. Here, the number of times of the free game is determined based on a game outcome of the sub game. Then, after the free game is successively executed the determined number of times, the free game is terminated and the game mode is switched to the base game again. Note that the procedure of the free game is the same as the base game except for in that the free game does not require any gaming value (credit) corresponding to a bet amount to be spent at a time of starting the game, and in that the free game is automatically and successively executed without requiring the player to operate the operation buttons 26. Accordingly, the detailed description of the procedure is omitted here.

Next, with reference to FIG. 8, a description will be furnished as to wining combinations and the respective payout amounts in a case where the base game and the free game are executed by using the reels 5 to 7 in the slot machine 1 according to this embodiment. FIG. 8 is a payout table indicating wining combinations and payout amounts of the respective wining combinations in a case where the base game or the free game is executed by using the reels 5 to 7.

Here, the payout amounts shown in FIG. 8 are payout amounts where a bet amount is “1”. Accordingly, when a bet amount is “1”, the payout amount exactly shown in FIG. 8 is provided. When a bet amount is “2” or more, a payout amount obtained by multiplying the bet amount by the payout amount shown in FIG. 8 is provided. Note that the bet amount used during the free game is determined to be one equal to the bet amount in the base game immediately before the start of the free game.

Thus, when three “CHANCE” symbols are rearranged on the payline L in the main liquid crystal panel 11B, a payout amount obtained by multiplying the bet amount by 10 credits is provided. Moreover, if during the base game, the player wins a start trigger for the sub game and thereby the sub game is executed in parallel with the base game. Incidentally, if the “CHANCE” symbols are rearranged during the free game, only a payout amount obtained by multiplying the bet amount by 10 credits is provided.

Instead, when three “BLUE7” symbols are rearranged on the payline L in the main liquid crystal panel 11B, a payout amount obtained by multiplying the bet amount by 10 credits is provided. When three “BELL” symbols are rearranged on the payline L in the main liquid crystal panel 11B, a payout amount obtained by multiplying the bet amount by 8 credits is provided. Similarly, a payout amount is set for each of the winning combinations shown in FIG. 8. However, when a combination composed of three symbols rearranged on the payline L in the main liquid crystal panel 11B does not agree with any winning combination shown in FIG. 8, the combination loses, and no payout is made for the loss.

Subsequently, with referring to FIG. 12, a description will be furnished as to the sub game started if a combination obtained during the aforementioned base game is one in which three “CHANCE” symbols 92 are rearranged on the payline L. When the sub game starts, one of various types of sub games is first selected by lottery. For example, this embodiment employs five types of sub games of a “shuffle card game”, a “spot the difference”, a “horse racing game”, a “memory” and a “quiz”, as shown in FIG. 12. The sub games give individually different winning conditions and losing conditions to a player, and employ the different challenge levels imposed on the player to satisfy the respective winning conditions. Moreover, the various types of sub games each are executed in accordance with input operations by the player.

In addition, as shown in FIG. 9, a lottery result of the sub game is displayed by using a scroll area 93 on the main liquid crystal panel 11B immediately after the start of the sub game. Specifically, the game names of the targeted five types of sub games are displayed, in turn, in a scrolling manner in the scroll area 93, and the game name of a sub game selected by lottery is finally stopped and displayed in the scroll area 93.

Hereinafter, the sub game is described by taking, as an example, a case where the “shuffle card game” is selected as the sub game. FIGS. 10 and 11 are diagrams showing game screens displayed on the main liquid crystal panel 11B in a case where the “shuffle card game” is selected as the sub game. When the “shuffle card game” is executed, three cards 94 to 96 are displayed below the display windows 15 to 17 on the main liquid crystal panel 11B. One of the three cards 94 to 96 is a “winning card” on which characters “WIN” are drawn, and the other two cards are “losing cards” on which nothing is drawn. The three cards 94 to 96 are turned upside down so as to be indistinguishable from each other, then are shuffled, and thereafter, are arranged in a line as shown in FIG. 10. Then, the player selects one card among the arranged three cards 94 to 96 by using the touch panel 18. As a result, when the player picks the “winning card” having the characters “WIN” drawn thereon as shown in FIG. 11, the player wins. On the other hand, when the player picks the “losing card” having nothing drawn thereon, the player loses. At this time, a win/lose display portion 97 displays both the number of times in a case where the player satisfies the winning condition, and the number of times in a case where the player satisfies the losing condition. Once the player satisfies the winning condition three times, the sub game is completed and the free game is executed instead of the base game. At this time, the number of times of the free game is determined based on the game outcome of the sub game. For example, in the “shuffle card game”, the number of times of the free game is changed according to the number of picked cards required to be picked by the player to satisfy the winning condition three times. In the case where the player satisfies the winning condition by tree trials, four trials and five trials, the player is allowed to play the free game 20, 10 and 5 times, respectively. On the other hand, in the case where the player satisfies the losing condition three times, the sub game is terminated and the base game is continuously executed.

Hereinafter, a main control program executed in the slot machine 1 according to this embodiment will be described in detail with referring to the drawings. FIG. 13 is a flowchart of the main control program.

First, when a power switch is turned on (power is on), the controller 41 activates the main control board 71 and the sub-control board 72, and then, performs initialization processing in step (hereinafter, abbreviated as S) 1. In this initialization processing, the main CPU 42 executes a BIOS stored in the ROM 44. More specifically, the main CPU 42 expands, into the RAM 43, compressed data incorporated in the BIOS, and then, executes the BIOS expanded in the RAM 43 as well as diagnoses and initializes various peripheral devices. In addition, the main CPU 42 writes the game program and other programs from the ROM 44 to the RAM 43, and obtains data for payout rate setting and country identification information. Moreover, the main CPU 42 also performs authentication processing for each program during the execution of the initialization processing.

Thereafter, at S2, the main CPU 42 reads the game program and the other programs from the RAM 43, and performs main game processing by executing these programs. In the slot machine 1 according to this embodiment, the game is executed by performing this main game processing. Then, the main game processing is repeatedly executed while power is supplied to the slot machine 1.

Next, sub-processing for S2 in the above-mentioned main game processing will be described based on FIG. 14. FIG. 14 is a flowchart of the main game processing program in the slot machine 1 according to this embodiment. Incidentally, each of the programs shown below in FIGS. 14 and 15 is stored in the ROM 44 or the RAM 43, and is executed by the main CPU 42.

As shown in FIG. 14, at S11, first, the main CPU 42 performs start accepting processing. At the time of this start accepting processing, a player inserts coins and performs the bet operation using the BET button of the operation buttons 26. In addition, the main CPU 42 causes each of the display windows 15 to 17 in the main liquid crystal panel 11B to become transparent or maintain the transparent state by transmitting a control signal to the sub-control board 72.

Thereafter, at S12, the main CPU 42 determines whether or not the start button of the operation buttons 26 is depressed. This determination is made based on a signal inputted to the main CPU 42 in response to the press of the start button. Here, when the start button is not depressed (S12: NO), the routine reverts to the start accepting processing (S11) again. Thereby, the player is allowed to perform an operation for correcting the bet amount or the like. On the other hand, when the start button is depressed (S12: YES), the main CPU 42 subtracts the bet amount set in accordance with the above bet operation, from the credit amount currently owned by the player, and stores the bet amount as bet information in the RAM 43.

After that, at S13, the main CPU 42 performs symbol lottery processing for the base game to select symbols to be arranged in the main liquid crystal panel 11B. More precisely, through the execution of the first lottery program stored in the RAM 43, the main CPU 42 samples random number values from numeric values within a predetermined range of random numbers, and determines symbols (in other words, the stop positions of the reels 5 to 7) to be arranged on the payline L by using the sampled random number values and the symbol weighting data.

Next, at S14, the main CPU 42 performs reel rotating processing. Specifically, the main CPU 42 causes the motor drive circuit 52 to drive each of the motors M1, M2 and M3, thereby causing each of the reels 5 to 7 to start rotating. After that, the main CPU 42 determines effect patterns for a unit of the game (patterns for displaying images on the main liquid crystal panel 11B, for outputting sounds form the speaker 31 and so on), and causes the sub-control board 72 and the like to start the effect in accordance with the determined effect patterns by instructing the sub-control board 72 and the like. Thereafter, upon arrival of a predetermined timing of stop when each of the reels 5 to 7 stops rotating, the main CPU 42 performs reel stop processing, thereby causing each of the reels 5 to 7 to stop via the control of the motor drive circuit 52 in accordance with the code number stored in the RAM 43. In this way, the combination of symbols determined at S13 mentioned above is rearranged on the payline L in the main liquid crystal panel 11B.

Then, at S15, the main CPU 42 determines whether or not the combination of symbols arranged on the main liquid crystal panel 11B is agreed with any winning combination to which a predetermined prize is to be awarded. This determination is made based on the code numbers or the like, of the respective reels 5 to 7 stored in the RAM 43.

As a result, when it is determined that the combination is one of the winning combinations (S15: YES), the routine proceeds to S16. On the other hand, when it is determined that the combination is not any of the winning combinations (S15: NO), the main game processing is terminated. Note that, when the game is continuously started as the next game, the processing following S11 is performed again.

At S16, the main CPU 42 notifies the player of a type of an established winning combination and the content of its prize, by displaying these on the main liquid crystal panel 11B. For example, as shown in FIG. 7, when three “BELL” symbols 91 are displayed on the payline L under the condition of a bet amount of 2, the characters “BELL×3” are displayed on the main liquid crystal panel 11B. In addition, 16, which is a number equivalent to a credit amount to be paid out, is also displayed at the payout amount display portion 19.

Subsequently, at S17, the main CPU 42 determines whether or not a start trigger for the sub game is established. Specifically, the start trigger for the sub game is determined as being established if three “CHANCE” symbols 92 are rearranged on the payline L at the main liquid crystal panel 11B.

As a result, when the start trigger for the sub game is determined as being established (S17: YES), the routine proceeds to the processing for the sub game (S18). Note that, the processing for the sub game will be described later in detail by using FIG. 15. On the other hand, when the start trigger for the sub game is determined as not being established (S17: NO), the routine proceeds to S22.

Then, at S19, the main CPU 42 determines whether or not the player satisfies the winning condition a predetermined number times or more (for example, three times or more) in the sub game executed in aforementioned S18. Here, the winning conditions for the player differ among the types of executed sub games as shown in FIG. 12. For example, when the “shuffle card game” is selected as the sub game, the player wins if the player picks the “winning card” having the character “WIN” drawn thereon from among multiple cards displayed on the main liquid crystal panel 11B, as shown in FIG. 11. Instead, when the “spot the difference” is selected as the sub game, the player wins if the player spots a point different between two images displayed on the main liquid crystal panel 11B. Alternatively, when the “horse racing game” is selected as the base game, the player wins if the player spots a winner of a horse race, among multiple racing horses displayed on the main liquid crystal panel 11B. Otherwise, when the “memory” is selected as the sub game, the player wins if the player makes up a pair by turning, a one-by-one basis, two cards displayed on the main liquid crystal panel 11B. Alternatively, when the “quiz” is selected as the sub game, the player wins if the player selects a correct choice as an answer to a question displayed on the main liquid crystal panel 11B.

When it is determined that the player satisfies the winning condition the predetermined number of times or more (S19: YES), a determination is firstly made as to the number of times in a case where the free game is to be executed (S20). Here, the number of times of the free game determined at S20 mentioned previously is based on the game outcome of the sub game executed at S18 mentioned previously. For example, when the sub game is the “shuffle card game”, the number of times of the free game changes according to the number of cards required to be picked by the player to satisfy the winning condition three times. To be more precise, when the player satisfies the winning condition by tree trials, four trials and five trials, the player is allowed to play the free game 20, 10, and 5 times, respectively.

Then, after the number of times of the free game is determined, the routine proceeds to free game processing (S21), whereby the game mode is switched from the base game to the free game. In the free game processing, the symbol lottery processing and reel rotating processing are successively and repeatedly executed, without requiring any gaming value to be spent, the number of times determined in S20 mentioned previously. During the free game, if the winning combinations are established, the prizes based on the respective winning combinations (see FIG. 8) are cumulatively added up. Incidentally, the symbol weighting data used for selecting a symbol by lottery during the free game may be the same as that of the base game, or alternatively, may be one allowing the winning combinations to be established with a higher possibility. On the other hand, when it is determined that the player does not satisfy the winning condition the predetermined number or more times (S19: NO), the routine proceeds to S22 without executing the free game.

Then, at S22, the main CPU 42 pays out, to the player, the prize that is based on the established winning combination. Here, when the CASHOUT button in the operation buttons 26 is depressed, the credit amount can be paid out as coins (1 credit is equivalent to 1 coin) corresponding to the credit amount, or can be paid out as a barcode-attached ticket. Note that, when the free game is executed, the prizes cumulatively added up during the free game are collectively provided to the player.

Next, sub-processing for S18 of the aforementioned sub game processing will be described based on FIG. 15. FIG. 15 is a flowchart of a sub-processing program of the sub game processing in the slot machine 1 according to this embodiment.

First, at S31, the main CPU 42 performs lottery processing for selecting one sub game among the various types of sub games. Specifically, the main CPU 42 selects one of the five types of sub games shown in FIG. 12, by executing the second lottery program included in the game program. In addition, the main CPU 42 executes the third lottery program, thereby setting various kinds of parameters needed to execute the selected sub game.

Then, at S32, the main CPU 42 displays, on the main liquid crystal panel 11B, a game screen based on the sub game selected at S31 mentioned above, and proceeds with the sub game based on the game screen displayed on the main liquid crystal panel 11B. Incidentally, the sub game is executed in accordance with player's input operations received through the touch panel.

Thereafter, at S33, the main CPU 42 determines whether or not the player satisfies the winning condition in the sub game. Here, the winning conditions for the player differ among the types of executed sub games as shown in FIG. 12. The challenge levels imposed on the player to satisfy the respective winning conditions also differ among the types of sub games.

Then, when it is determined that the player satisfies the winning condition (S33: YES), the number of times in a case where the player satisfies the winning condition is counted (S34). When the number of times in a case where the player satisfies the winning condition is counted a predetermined number of times (for example, three times), the sub game is terminated. In contrast, when it is determined that the player does not satisfy the winning condition (S33: NO), the routine proceeds to S35.

In addition, at S35, the main CPU 42 determines whether or not the player satisfies the losing condition in the sub game. Here, the losing conditions for the player differ among the types of executed sub games as shown in FIG. 12.

Thereafter, when it is determined that the player satisfies the losing condition (S35: YES), the number of times in a case where the player satisfies the losing condition is counted (S36). When the number of times in a case where the player satisfies the losing condition is counted a predetermined number of times (for example, three times), the sub game is terminated. In contrast, when it is determined that the player does not satisfy the losing condition (S35: NO), the routine proceeds to S37.

At S37, the main CPU 42 determines whether or not a condition for terminating the sub game is satisfied. As for the slot machine 1 according to this embodiment, the condition for terminating the sub game is determined as being satisfied when the number of times in a case where the player satisfies the winning condition or the number of times in a case where the player satisfies the losing condition reaches a predetermined number of times (for example, three times). Instead, a condition where a predetermined time elapses after the start of the sub game may be employed as the condition for terminating the sub game. Otherwise, the condition for terminating the sub game may be a condition where a total sum of the number of times in a case where the player satisfies the winning condition and the number of times in a case where the player satisfies the losing condition reaches a predetermined number of times (for example, four times).

Then, when the condition for terminating the sub game is determined as satisfied (S37: YES), the sub game is terminated and the routine proceeds to the aforementioned determination processing at S19. Thereafter, as described above, when it is determined that the player satisfies the winning condition the predetermined number of times or more, the free game is executed after switching from the base game. On the other hand, when the condition for terminating the sub game is determined as not being satisfied (S37: NO), the routine returns to S33.

As has been described above, in the slot machine 1 according to this embodiment, when the base game is started, all the reels 5 to 7 start rotating, and the symbols are arranged on the main liquid crystal panel 11B after the predetermined time has elapsed (S14). At this time, if the arranged symbols form the combination in which three “CHANCE” symbols 92 are arranged on the payline L (S17: YES), the sub game, which is different from the base game, is executed during the base game (S18). Then, if the player satisfies the winning condition the predetermined number of times of more in the sub game (S19), the game mode is switched from the base game to the free game, and then, the free game is executed (S21). Accordingly, the condition for starting the free game may be variously changed without being limitative to a game outcome of the base game. In addition, the player is allowed to play the sub game in addition to the base game, thus avoiding monotony of the game. This enables the player to continue playing the game for a long time, thus enhancing the entertainment of the game. In addition, the free game is started when it is determined that the player satisfies the winning condition the predetermined number of times of more in the sub game, and this promotes player's expectations for the start of the free game with the progress of the sub game. Moreover, during the base game, the sub game is executed when a combination including the particular symbols (“CHANCE” symbols 92) is arranged on the main liquid crystal panel 11B in the base game. This also promotes player's expectations for an event where the particular symbols are arranged in the base game. Further, since there are multiple types of sub games, the executed sub game is changed for every session of the sub game, thereby avoiding monotony of the game. Moreover, the condition for switching to the free game can also be changed for every session of the sub game, so that the entertainment of the game is enhanced. Additionally, the multiple types of sub games employ the different challenge levels to be imposed on the player to satisfy the respective winning conditions, whereby the player feels a different level of expectations depending on the type of the selected sub game. Hence, the slot machine 1 provides the player with such a different level of expectations, depending on the type of the selected sub game, thereby enhancing the entertainment of the game. Furthermore, the slot machine 1 is capable of providing the game that lets even a player with a poor gaming technique enjoy playing sufficiently and prevents a player with a good gaming technique from getting bored.

In addition, the game outcome of the sub game is used as a base for determining the number of times of the free game executed subsequently to the sub game (S20). Thus, according to the game outcome of the executed sub game, the player feels a different level of expectations of acquiring a large amount of gaming values in the subsequently-executed free game. Accordingly, the entertainment of the game is enhanced.

It should be noted that the present invention is not absolutely limitative to the aforementioned embodiment, but can be improved or modified without deviating from the essence of the present invention. For example, in this embodiment, when the three particular symbols (“CHANCE” symbols 92) are arranged on the payline L during the base game, the sub game is executed. However, the condition for executing the sub game may be another condition. For example, the sub game may be executed when the arranged symbols includes at least one particular symbol (“CHANCE” symbol 92). Otherwise, the sub game may be executed, like a mystery bonus, no matter what symbols are arranged.

Moreover, in this embodiment, the free game is executed when the player satisfies the winning condition the predetermined number of times of more during one session of the sub game. Nevertheless, the number of times in a case where the player satisfies the winning condition may be accumulated over several sessions of the sub game, and the free game may be executed when the cumulative number of times reaches a predetermined number of times or more. In other words, a player gradually satisfies a condition for executing the free game by playing several sessions of the sub game.

Furthermore, the slot machine 1 of this embodiment is a slot machine for the slot game using three mechanical reels, but may be one for a slot game using 5 or 9 reels. Instead, the slot machine 1 may also be a slot machine using video reels.