Abstract:
In a game processor GP that enable a player to play a plurality of games interrelated to each other, flash memory  12  stores a plurality of game programs PG interrelated to each other. SRAM  13  readably and writably stores backup data DG representing the progress of each of games A, B, and C. The player selects one of the game programs PG through a controller  70  to start game play. A deciding unit (CPU)  61  decides whether there is backup data DG for any game related to the game specific to the selected game. Based on a decision as to the backup data DG, a game program changer changes part of the game program PG.

Description:
FIELD OF THE INVENTION 
     The present invention relates to game processors that enable players to play various games with scenarios which vary according to the progress of each game, thereby achieving great versatility in possible game content. The present invention also relates to information storage media storing a game program therein to enable such versatility. 
     BACKGROUND AND SUMMARY OF THE INVENTION 
     Conventionally, game processors exist for executing game programs which exhibit a varied scenario. One example of such a game processor is disclosed in Japanese Patent No. 2930237 (hereinafter referred to as “background art”). In this background art, selecting any one of a set of hero characters provided in the game activates an event that has been uniquely set for the selected character. In this fashion, the game contents can be varied. 
     In this manner, the background art achieves versatility in game contents by activating an event unique to each game character. However, the game contents are always the same as long as the same character is selected. Therefore, the game appears to become more predictable as the game is played again and again. Thus, players tend to lose interest in the game and become bored with the game. 
     An advantage of the exemplary embodiments is that a game processor and information storage medium storing a game program are provided which varies each game in scenario according to the progress of other interrelated games. 
     A first aspect of the exemplary embodiments is directed to a game processor that enables a player to play a plurality of games interrelated to each other, the game processor comprising: 
     a game program storage for storing a plurality of game programs interrelated to each other; 
     a backup data storage for writably and readably storing backup data representing progress of each of the games separately played; 
     an operating unit for providing an instruction for selecting one of the plurality of game programs stored in the game program storage, and starting and playing a game specific to the selected game program; 
     a deciding unit for deciding, when the operating unit provides the instruction for starting the game, whether the backup data for another game related to the specific game is stored; 
     a game program changer for changing part of the selected game program, based on a decision made by the deciding unit as to the backup data; 
     a reader for reading the changed game program; and an image processing unit for carrying out image processing for the game program read by the reader and for making a display image changed based on the instruction provided by the operating unit. 
     As described above, in the first aspect, scenarios varied in content for one game can be generated according to the progress of other games related to the game now being played. 
     According to a second aspect, in the first aspect, the backup data storage includes a clear information storage area for storing clear information about any cleared game, and 
     the deciding unit decides whether the clear information is written in the backup data for another game related to the specific game. 
     As described above, in the second aspect, players can have fun with playing the same game varied in scenario, according to the state of related games. 
     According to a third aspect, in the first aspect, each of the game programs stored in the game program storage is composed of a plurality of scenario units varied in type, and 
     the game program changer selects, based on the decision made by the deciding unit, a predetermined scenario unit from the plurality of scenario units varied in type to compose the game program. 
     As described above, in the third aspect, one scenario is composed of a plurality of scenario units. Of the scenario units, a specific scenario unit is selected based on whether other related games have been cleared or not. Thus, the scenario varied in content can be easily composed. 
     According to a fourth aspect, in the first aspect, the game program storage is a readable and writable nonvolatile memory larger in capacity than each of the games; 
     the nonvolatile memory stores the game programs for at least two games that are interrelated to each other and played in a predetermined order; and 
     the backup data storage has storage capacity capable of individually storing the backup data for each of the at least two games. 
     According to a fifth aspect, in the first aspect, the game program storage stores the plurality of game programs interrelated to each other for games that are same in game genre and hero character but different in scenario at least in part. 
     A sixth aspect is directed to a game information storage medium provided with an operating unit and a processing unit, the game information storage medium comprising: 
     a game program storage medium for storing a plurality of game programs interrelated to each other; and 
     a backup data storage medium for writably and readably storing backup data representing progress of each of the games separately played, wherein 
     the game program storage medium comprises; 
     a decision program for deciding whether backup data for another game related to a game specified by the operating unit is stored; 
     a change program for changing part of the game program for the specified game, based on a decision made by the decision program as to the backup data; 
     a read control program for reading the changed game program; 
     an image processing program for carrying out image processing for the game program read by the read control program and for making a display image changed based on an operation of the operating unit. 
     A seventh aspect is directed to a medium storing a game program for controlling a game processor that enables a player to play a plurality of games interrelated to each other, 
     the game program when executed performing the steps of: 
     storing a plurality of game programs interrelated to each other; 
     writably and readably storing backup data as to progress of each of the games; 
     carrying out an operation by providing an instruction for selecting one of the plurality of game programs, and starting and playing a game specific to the selected game program; 
     deciding, when an instruction is provided for starting the specific game, whether the backup data for another game related to the specific game is stored; 
     changing part of the selected game program, based on a decision made in the deciding step as to the backup data; 
     reading the changed game program; and 
     carrying out image processing for the read game program and for making a display image changed based on the operation. 
     These and other objects, features, aspects and advantages of the present invention will become more apparent from the following detailed description of the present invention when taken in conjunction with the accompanying drawings. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a block diagram showing the structure of a game processor according to the present invention; 
     FIG. 2 is a schematic diagram showing the structure of storage areas of flash memory and SRAM shown in FIG. 1; 
     FIG. 3 is a table showing scenario unit selection criteria based on a relation between related games in the game processor shown in FIG. 1; 
     FIG. 4 is a table showing a relation between scenarios composed based on the scenario unit selection criteria shown in FIG.  3  and scenario units; 
     FIG. 5 is a flow chart showing a scenario generation process in the game processor according to the present invention; 
     FIGS. 6,  7 , and  8  are flowcharts showing a process in step # 100  shown in FIG. 5; and 
     FIGS. 9, and  10  are flowcharts showing a process in step # 200  shown in FIG.  6 . 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     With reference to FIG. 1, a game processor according to one embodiment to the present invention is described. A game processor GP according to the present embodiment includes a program source  100  and a game machine  200 . The program source  100  stores information such as a program required for game execution in the game machine  200 . The program source  100  is so structured as to be detachably connected to the game machine  200 . 
     The program source  100  preferably includes a connector  11 , flash memory  12 , SRAM  13 , a memory controller  14 , and a backup IC  15 . The program source  100  is generally packaged as a game cassette. In this sense, the program source is hereinafter also referred to as a game cassette  100 . The flash memory  12  and the SRAM  13  are connected through a data bus DB 1  to the connector  11 , and also through an address bus AB 1  to the memory controller  14 . The memory controller  14  is connected through an address bus AB 2  to connector  11 . 
     As is well known, a flash memory is a rewritable nonvolatile memory. In the present embodiment, the flash memory  12  has, for example, a 32M-bit storage capacity and is used for storing a game program, as described later. In the exemplary embodiment, the flash memory  12  is divided into eight 4M-bit blocks. 
     The SRAM  13  is static RAM for holding storage contents as long as it is supplied with electric power. In the present embodiment, the SRAM  13  has, for example, a 256K-bit storage capacity and is used for storing game backup data, such as data relating to cleared stages, captured items, and raised characters. In the exemplary embodiment, the SRAM  13  is divided into sixteen 16K-bit blocks. 
     The memory controller  14  in part operates to convert an address provided through the address bus AB 2  by a cassette writer (not shown) or the game machine  200  into an address complying with memory mapping in the flash memory  12  and the SRAM  13 . The backup IC  15  supplies the SRAM  13  with electric power coming from the cassette writer or the game machine  200  when the program source (game cassette)  100  is set therein. 
     The flash memory  12  and the SRAM  13  have a complementary relationship with each other, as being selected by a chip-select signal CE 1  coming from the memory controller  14  and a chip-select signal CE 2  coming from the backup IC  15 , respectively. That is, when the flash memory  12  is selected, the SRAM  13  is not selected, and vice versa. 
     In this complementary relation, the flash memory  12  and the SRAM  13  are provided with data and addresses through the same data bus and address bus, but only the memory chip corresponding to the provided address is enabled to be accessed. The chip-select signal CE 2  is generated by the backup IC  15  based on a 1-bit decode signal DS from the memory controller  14  and how much power is supplied to the SRAM  13 . 
     Especially when the program source  100  set in the cassette writer or the game machine  200  is powered on to supply power, noise may be mixed in the address bus AB 1  due to a transient response caused by power-on. If the noise happens to indicate any address in the SRAM  13 , the memory controller  14  erroneously produces the decode signal DS and carries out unwanted writing in that address. 
     Therefore, the backup IC  15  monitors the voltage supplied by a power source in the cassette writer or the game machine  200 . When powered on, the backup IC  15  does not provide the chip-select signal CE 2  to the SRAM  13  until the voltage is stabilized at a predetermined value (approximately 4.5V). Thus, undesired, erroneous writing can be prevented at the time of power-on (power supply) 
     With respect to the address provided by the memory controller  14  through the address bus AB 1  to the flash memory  12 , the upper three bits are used to specify any one of eight blocks in the flash memory  12 . Similarly, the upper four bits thereof are used to specify any one of sixteen blocks in the SRAM  13 . 
     The game machine  200  includes, for example, a CPU  61 , a PPU (picture (i.e., graphics) processing unit)  62 , a working RAM  63 , a video RAM  64 , an I/O interface  65 , and a connector  66 . The CPU  61  is connected to the connector  66  through a data bus DB 3  and an address bus AB 3 ; to the PPU  62  through a data bus DB 4  and an address bus AB 4 ; and to the working RAM  63  through a data bus DB 5  and an address bus AB 5 . The video RAM  64  is connected to the PPU  62  through a data bus DB 6  and an address bus AB 6 . Outputs from the PPU  62  are provided to a display unit  80  such as a television receiver. 
     When a game is played, the connector  11  of the program source  100  is inserted into the connector  66  of the game machine  200 . Thus, the flash memory  12  and the SRAM  13  are controlled by CPU  61 . Then, CPU  61  reads a game program from the flash memory  12  to start a game operation. Also, the CPU  61  reads game backup data from the SRAM  13  as required to set parameters for the game operation. A controller  70  is operated by the player to provide various instructions and commands to the CPU  61 . 
     The working RAM  63  stores various data required for arithmetic operations by the CPU  61 . The PPU  62  generates, based on an instruction from the CPU  61 , display data from character data stored in the video RAM  64 . This display data is provided to the display unit  80  for display. As such, the PPU  62  relieves the CPU  61  of the requirement of generating display data, and enables the primary game operation quickly. The above-described game machine  200  and cassette  100  are set forth as one example of many possible game machines and storage media that may be used herein. For example, the game machine  200  and information storage media associated therewith may be implemented by the video game system described in application Ser. No. 09/465,754 and filed on Dec. 17, 1999, which application is hereby incorporated herein by reference. 
     With reference to FIG. 2, exemplary data structures within storage areas of the flash memory  12  and the SRAM  13  are described in detail. The storage area of the flash memory  12  according to the present embodiment includes a main program area APm and a game program area APg. The main program area APm stores main programs AP such as a game selection program, a decision program, a change program, and a read/write control program. 
     The game program area APg stores a game A program PGa, a game B program PGb, and a game C program PGc, each used to execute a different game. In the present embodiment, three different game programs for a game A, a game B, and a game C are stored. Needless to say, however, any arbitrary number of game programs may be stored as long as the capacity of the flash memory  12  will permit such storage. 
     The game A program PGa includes program data required for executing the game A, such as a start setting program, an image processing program, a game title (version), scenario units a 1 , a 2 , a 3  to a 7 , and a 8  composing a scenario SA, and character data. Similarly, the game B program PGb includes program data required for executing the game B, such as a start setting program, an image processing program, a game title (version), scenario units b 1 , b 2 , b 3  to b 7 , and b 8  composing a scenario SB, and character data. 
     Also, the game C program PGc includes program data required for executing the game C, such as a start setting program, an image processing program, a game title (version), a scenario units c 1 , c 2 , c 3  to c 7 , and c 8  composing a scenario SC, and character data. 
     In the present embodiment, these games A, B, and C are, for example, related to one another as being the same in genre and hero character but different in part with respect to each scenario. 
     The SRAM  13  stores backup data for the game programs PGa, PGb, and PGc written in the game program area APg of the flash memory  12 . 
     For example, game A backup data DGa includes a game title (version) DTa, an identification code of the player, progress data DPa indicating the progress of the game A, clear data DCa, and others all for the game A program PGa. Similarly, game B backup data DGb and game B backup data DGc include backup data for the game B program PGb and the game C program PGc, respectively, as shown in FIG.  2 . 
     While game A is being executed, the game title DTa is automatically recorded in the game A backup data DGa of the SRAM  13 . Similarly, the clear data DCa is automatically recorded, once the player clears the game A. In the clear data DCa, the order of clearing is recorded based on the presence or absence of the clear data DCb and DCc for the related games B and C. 
     In the exemplary embodiment, the progress data DPa is not recorded until the player willingly stores the game state when suspending or ending the game. When the progress data DPa is recorded, the game title DTa may be recorded at the same time. In the present embodiment, the main programs AP and the game programs PG are stored in the flash memory  12  while the backup data DG is stored in the SRAM  13 . Alternatively, all of these programs may be stored in a single memory. 
     With reference to a table showing exemplary scenario unit selection criteria in FIG. 3, the generation of scenarios differing in content based on the situation when the player starts the game will be described. First, the game A is composed by selectively combining a plurality of scenario units. 
     In the present embodiment, the scenario SA of the game A is composed by selectively combining any of the scenario units a 1 , a 2 , a 3 , a 4 , a 5 , a 6 , a 7 , and a 8 . Alternatively, the scenario SA may be composed of an adequate number of scenario units within the limitations of the capacity of the flash memory  12 . 
     As shown in FIG. 3, the scenario units a 1  and a 2  are unconditionally selected to compose the scenario SA when the game A is played. 
     The scenario unit a 3  is selected only when the game A is played for the first time. 
     The scenario unit a 4  is selected when the game A is played with only the game B already cleared. 
     The scenario unit a 5  is selected when the game A is played with only the game C already cleared. 
     The scenario unit a 6  is selected when the game A is played with the game B and then the game C already cleared. 
     The scenario unit a 7  is selected when the game A is played with the game C and then the game B already cleared. 
     The scenario unit a 8  is unconditionally selected when the game A is played. 
     With reference to FIG. 4, the generation of the game scenario SA having different stories by selectively combining the scenario units based on the criteria will be described. As shown in FIG. 4, when the game A is played for the first time, a scenario SAα composed of the scenario units a 1 , a 2 , a 3  and a 8  is generated, based on the criteria described with reference to FIG.  3 . 
     When the game A is played with only the game B already cleared, a scenario SAβ composed of the scenario units a 1 , a 2 , a 4 , and a 8  is generated. 
     When the game A is played with only the game C already cleared, a scenario SAγ composed of the scenario units a 1 , a 2 , a 5 , and a 8  is generated. 
     When the game A is played with the game B and then the game C already cleared, a scenario SAδ composed of the scenario units a 1 , a 2 , a 6 , and a 8  is generated. 
     When the game A is played with the game C and then the game B already cleared, a scenario SAε composed of the scenario units a 1 , a 2 , a 7 , and a 8  is generated. 
     As such, in the present embodiment, five scenarios SAα, SAβ, SAγ, SAδ, and SAε each composed of four scenario units and differing in story from one anther can be generated in the game A. In any of these five scenarios SAα, SAβ, SAγ, SAδ, and SAε, the first, second, and last scenario units are always a 1 , a 2 , and a 8 , respectively. 
     In other words, based on the criteria shown in FIG. 3, the third scenario unit is selected from among the five scenario units a 3 , a 4 , a 5 , a 6 , and a 7  according to the situation at the time of starting the game. As such, in the present embodiment, the first, second, and fourth scenario units are fixed. Alternatively, every scenario unit may be selected from all scenario units a 1  to a 8 , or the third may be fixed. Furthermore, needless to say, the game scenario SA may be composed by combining an arbitrary number of scenario units, and every scenario unit may be selected fixedly or based on the criteria. 
     As clearly shown in FIGS. 3 and 4, also for the games B and C, various scenarios SB and SC are generated by selecting scenario units according to the situation at the time of starting the game. 
     More specifically, for the game B, the scenario units b 1  and b 2  are unconditionally selected when the game B is played. 
     The scenario unit b 3  is selected only when the game B is played for the first time. 
     The scenario unit b 4  is selected when the game B is played with only the game A already cleared. 
     The scenario unit b 5  is selected when the game B is played with only the game C already cleared. 
     The scenario unit b 6  is selected when the game B is played with the game A and then the game C already cleared. The scenario unit b 7  is selected when the game B is played with the game C and then the game A already cleared. 
     The scenario unit b 8  is unconditionally selected when the game B is played. 
     Therefore, when the game B is played for the first time, a scenario SBα composed of the scenario units b 1 , b 2 , b 3  and b 8  is generated. 
     When the game B is played with only the game A already cleared, a scenario SBβ composed of the scenario units b 1 , b 2 , b 4 , and b 8  is generated. 
     When the game B is played with only the game C already cleared, a scenario SBγ composed of the scenario units b 1 , b 2 , b 5 , and b 8  is generated. 
     When the game B is played with the game A and then the game C already cleared, a scenario SBδ composed of the scenario units b 1 , b 2 , b 6 , and b 8  is generated. 
     When the game B is played with the game C and then the game A already cleared, a scenario SBε composed of the scenario units b 1 , b 2 , b 7 , and b 8  is generated. 
     For the game C, the scenario units c 1  and c 2  are unconditionally selected when the game C is played. 
     The scenario unit c 3  is selected only when the game C is played for the first time. 
     The scenario unit c 4  is selected when the game C is played with only the game A already cleared. 
     The scenario unit c 5  is selected when the game C is played with only the game B already cleared. 
     The scenario unit c 6  is selected when the game C is played with the game A and then the game B already cleared. 
     The scenario unit c 7  is selected when the game C is played with the game B and then the game A already cleared. 
     The scenario unit c 8  is unconditionally selected when the game C is played. 
     As a result, when the game C is first played, a scenario SCα composed of the scenario units c 1 , c 2 , c 3  and c 8  is generated. 
     When the game C is played with only the game A already cleared, a scenario SCβ composed of the scenario units c 1 , c 2 , c 4 , and c 8  is generated. 
     When the game C is played with only the game A already cleared, a scenario SCγ composed of the scenario units c 1 , c 2 , c 5 , and c 8  is generated. 
     When the game C is played with the game A and then the game B already cleared, a scenario SCδ composed of the scenario units c 1 , c 2 , c 6 , and c 8  is generated. 
     When the game C is played with the game B and then the game A already cleared, a scenario SCε composed on the scenario units c 1 , c 2 , c 7 , and c 8  is generated. 
     Also in scenario generation for the games B and C, the first, second and last scenario units are fixed in the present embodiment. Alternatively, every scenario unit may be selected from all scenario units based on the criteria, or the third may be fixed. Furthermore, needless to say, the game scenarios SB and SC may be composed by combining an arbitrary number of scenario units, and every scenario unit may be selected fixedly or based on the criteria. 
     In FIG. 4, the fourth column is provided for flags. In this flag column, flags F 1  to F 15  (not in particular order) are shown. These flags F 1  to F 15  correspond to “generation criteria” also shown in FIG. 4, and will be described later in detail with reference to FIGS. 6,  7 ,  8 ,  9 , and  10 . 
     Next, with reference to a flowchart shown in FIG. 5, a scenario generation operation by the game processor GP according to an exemplary embodiment of the present invention is now described. When the power source of the game processor GP is powered on to start the operation, in step S 2 , a menu screen for the games A, B, and C is displayed on the display unit  80 . Then, the procedure goes to a next step S 4 . 
     In step S 4 , based on the operation of the controller  70  by the player, it is decided whether any of the games A, B, and C displayed on the menu screen has been selected. If the player has not selected any game, No is decided, and the procedure returns to step S 2 . On the other hand, if any of the games A, B, and C has been selected, Yes is decided, and the procedure goes to a next step S 6 . 
     In step S 6 , the title or demo screen of the game selected in step S 4  is displayed on the display unit  80 . Then, the procedure goes to step S 8 . 
     In step S 8 , it is decided that the player has pressed a start button provided on the controller  70  to start the game selected in step S 4 . If No, the procedure returns to step S 6 , wherein displaying the title or demo screen continues until an input for game start is received from the player. On the other hand, if Yes, the procedure goes to a next step S 10 . 
     In step S 10 , it is decided whether the game selected in step S 4  and started in step S 8  has never been played before and is going to be played for the first time. This decision is made based on the game backup data DG recorded in the SRAM  13 . 
     That is, any of the clear data DC, the progress data DP, the game title DT for the selected game is recorded in the game backup data DG, it is decided whether the game has been previously played. 
     If Yes in step S 10 , the procedure goes to step S 16  through a check-at-start subroutine process in step # 100 . The check-at-start subroutine process in step # 100  will be described below in detail with reference to FIGS. 6,  7 , and  8 . 
     On the other hand, if No in step S 10 , that is, if the game to be started has been previously played, the procedure goes to step S 12 . 
     In step S 12 , the backup data for the selected game is read from the SRAM  13 . That is, the backup data to be read is any one of the game A backup data DGa, the game B backup data DGb, and the game C backup data DGc. Then, the procedure goes to a next step S 14 . 
     In step S 14 , a setting process required at the time of starting the game is carried out based on the read backup data, that is, any one of the game A backup data DGa, the game B backup data DGb, and the game C backup data DGc. Then, the procedure goes to step S 16 . 
     After the setting process for the selected game in step # 100  or step S 14 , the game program PG of the selected game is executed in step S 16 . The game is executed for a predetermined amount, and then the procedure goes to a next step S 18 . 
     In step S 18 , it is decided, based on the operation of the controller  70 , whether the player initiated an instruction for ending the game. If No, the procedure returns to step S 16  to continue executing the game for the predetermined amount. On the other hand, if Yes, the procedure goes to a next step S 20 . 
     In step S 20 , it is decided, based on the operation of the controller  70  and the state of execution of the game program, whether the player has cleared the game. If Yes, the procedure goes to step S 22 . 
     In step S 22 , clear data is written in the clear data area DC of the backup data DG in the SRAM  13 . Then, the procedure ends. 
     On the other hand, if No in step S 20 , that is, if the player has not yet cleared the game, the procedure goes to step S 24 . 
     In step S 24 , it is decided, based on the operation of the controller  70  and the state of the game program, whether the player initiated an instruction for storing the state of the play (progress) of the game before ending (suspending) the game. If Yes, the procedure goes to step S 26 . 
     In step S 26 , the progress data is written in the progress data area DP of the backup data DG in the SRAM  13 . Then, the procedure ends. 
     If No in step S 24 , that is, if the player did not clear the game nor make an instruction for storing the progress of the game, the procedure ends. 
     With reference to FIG. 6, the check-at-start subroutine in step # 100  will be described. 
     In the above-described step S 10 , if it is decided that the selected game is played for the first time, in step S 102 , the title of the selected game is read from the game program area APg of the flash memory  12 . Then, the procedure goes to step S 104 . 
     In step S 104 , as already described with reference to FIGS. 3 and 4, it is decided whether the backup data DG of any other games that affect selection of scenario units used for generating the scenario for the selected game is stored in the SRAM  13 . 
     In the present embodiment, the backup data DG, especially the clear data DC, is used for deciding which scenario units are selected. If Yes in step S 104 , the procedure goes to steps S 106  to S 128  shown in FIG. 7, steps S 130  to S 152  shown in FIG. 8, and then step S 154  shown in FIG. 6 or step # 200  of a game program setting subroutine. 
     If Yes in step S 104 , it is decided in step S 106  shown in FIG. 7 whether the clear data DC stored in the SRAM  13  is only the clear data DCa for the game A. If Yes, that is, if only the game A has been cleared, the procedure goes to a next step S 108 . 
     In step S 108 , it is decided whether the title of the game read in step S 102  is that of the game B. If Yes, that is, if the selected game is the game B, the procedure goes to a next step S 110 . 
     In step S 110 , the flag F 4  is set. Then, the procedure goes to step # 200  shown in FIG.  6 . That is, the flag F 4  indicates that only the game A has been cleared at the time of starting the game B. 
     On the other hand, if No, that is, if the only the game A has been cleared and the selected game is the game C, the procedure goes to step S 112 . 
     In step S 112 , the flag F 5  is set. Then, the procedure goes to step # 200  shown in FIG.  6 . That is, the flag F 5  indicates that only the game A has been cleared at the time of starting the game C. 
     If No in the above step S 106 , that is, if not only the game A but also other game have been cleared, the procedure goes to step S 114 . 
     In step S 114 , it is decided whether the clear data DC stored in the SRAM  13  is only the clear data DCb for the game B. If Yes, that is, if only the game B has been cleared, the procedure goes to a next step S 116 . 
     In step S 116 , it is decided whether the title of the game read in the above step S 102  is that of the game A. If Yes, that is, if the selected game is the game A, the procedure goes to a next step S 118 . 
     In step S 118 , the flag F 6  is set. Then, the procedure goes to step # 200  shown in FIG.  6 . The flag F 6  indicates that only the game B has been cleared at the time of starting the game A. 
     On the other hand, if No in step S 116 , that is, if only the game B has been cleared and the selected game is the game C, the procedure goes to step S 120 . 
     In step S 120 , the flag F 7  is set. Then, the procedure goes to step # 200  shown in FIG.  6 . The flag F 7  indicates that only the game B has been cleared at the time of starting the game C. 
     If No in the above step S 114 , that is, if not only the game B but also other games have been cleared, the procedure goes to step S 122 . 
     In step S 122 , it is decided whether the clear data DC stored in the SRAM  13  is only the clear data DCc for the game C. If Yes, that is, if only the game C has been cleared, the procedure goes to a next step S 124 . 
     In step S 124 , it is decided whether the title of the game read in the above step S 102  is that of the game A. If Yes, that is, if the selected game is the game A, the procedure goes to a next step S 126 . 
     In step S 126 , the flag F 8  is set. Then, the procedure goes to step # 200  shown in FIG.  6 . That is, the flag F 8  indicates that only the game C has been cleared at the time of starting the game A. 
     On the other hand, if No in step S 124 , that is, if only the game C has been cleared and the selected game is the game B, the procedure goes to step S 128 . 
     In step S 128 , the flag F 9  is set. Then, the procedure goes to step # 200  shown in FIG.  6 . That is, the flag F 9  indicates that only the game C has been cleared at the time of starting the game B. 
     If No in the above step S 122 , that is, if not only the game C but also other game have been cleared, the procedure goes to step S 130  shown in FIG.  8 . 
     In step S 130 , it is decided whether the clear data Dca and the clear data DCb are stored in the SRAM  13 . If Yes, that is, if the games A and B have been cleared, the procedure goes to a next step S 132 . 
     In step S 132 , it is decided whether the clear data DCa was stored preceding the clear data DCb. If Yes, that is, if the game A has been cleared before the game B, the procedure goes to a next step S 134 . 
     In step S 134 , the flag F 10  is set. Then, the procedure goes to step # 200 . That is, the flag F 10  indicates that the game A and then the game B have been cleared at the time of starting the game C. 
     On the other hand, if No in step S 132 , that is, if the game B has been cleared before the game A, the procedure goes to step S 136 . 
     In step S 136 , the flag F 11  is set. Then, the procedure goes to step # 200 . That is, the flag F 11  indicates that the game B and then the game A have been cleared at the time of starting the game C. 
     If No in the above step S 130 , that is, if not both of the games A and B have been cleared, the procedure goes to step S 138 . 
     In step S 138 , it is decided whether the clear data DCa and DCc are stored in the SRAM  13 . If Yes, that is, if the games A and C have already been cleared, the procedure goes to a next step S 140 . 
     In step S 140 , it is decided whether the clear data DCa was stored preceding the clear data DCc. If Yes, that is, if the game A has been cleared before the game C, the procedure goes to a next step S 142 . 
     In step S 142 , the flag F 12  is set. Then, the procedure goes to step # 200 . That is, the flag F 12  indicates that the game A and then the game C have been cleared at the time of starting the game B. 
     On the other hand, if No in step S 140 , that is, if the game C has been cleared before the game A, the procedure goes to step S 144 . 
     In step S 144 , the flag F 13  is set. Then, the procedure goes to step # 200 . That is, the flag F 13  indicates that the game C and then the game A have been cleared at the time of starting the game B. 
     If No in the above step S 138 , that is, if not both of the games A and C have been cleared, the procedure goes to step S 146 . 
     In step S 146 , it is decided whether the clear data DCb and DCc are stored in the SRAM  13 . If Yes, that is, if the games B and C have been already cleared, the procedure goes to a next step S 148 . 
     In step S 148 , it is decided whether the clear data DCb was stored preceding the clear data DCc. If Yes, that is, if the game B has been cleared before the game C, the procedure goes to step S 150 . 
     In step S 150 , the flag F 14  is set. Then, the procedure goes to step # 200 . That is, the flag F 14  indicates that the game B and then the game C have been cleared at the time of starting the game A. 
     On the other hand, if No in step S 148 , that is, if the game C has been cleared before the game B, the procedure goes to step S 152 . 
     In step S 152 , the flag F 15  is set. Then, the procedure goes to step # 200 . That is, the flag F 15  indicates that the game C and then the game B have been cleared at the time of starting the game A. 
     If No in step S 146 , that is, if not both of the games B and C have been cleared, the procedure goes to step S 154  shown in FIG.  6 . 
     As such, the flags F 4  to F 15  are set as corresponding to the scenario unit selection criteria. 
     If it is decided in step S 104  shown in FIG. 6 that the backup data DG is stored, the procedure goes through the process shown in FIGS. 7 and 8. Then, if no game has been cleared, none of the flags is set in the process shown in FIGS. 7 and 8, and the procedure goes to step S 154  shown in FIG.  6 . 
     Further, if it is decided in step S 104  that the backup data DG is not stored, any flag corresponding to the scenario unit selection criteria is not set, and then the procedure goes to step S 154 . In other words, any one of the flags F 4  to F 15  is not set at the time of starting the process in step S 154 . 
     In step S 154 , it is decided whether the title of the game read in the above step S 102  is that of the game A. If Yes, that is, if the selected game is the game A, the flag F 1  is set. Then, the procedure goes to the game program setting subroutine in step # 200 . That is, the flag F 1  indicates that the game A is played for the first time. 
     On the other hand, if No in step S 154 , that is, if the selected game is not the game A, the procedure goes to step S 158 . 
     In step S 158 , it is decided whether the title of the game read in step S 102  is that of the game B. If Yes, that is, if the selected game is the game B, the flag F 2  is set. Then, the procedure goes to step # 200 . That is, the flag F 2  indicates that the game B is played for the first time. 
     On the other hand, if No in step S 158 , that is, if the selected game is not the game B, the procedure goes to step S 162 . 
     In step S 162 , the selected game is the game C, and the flag F 3  is set. Then, the procedure goes to step # 200 . That is, the flag F 3  indicates that the game C is played for the first time. 
     Next, with reference to FIGS. 9 and 10, the game program setting subroutine in step # 200  will be described in detail. The process in step # 200  starts with the scenario unit selection criteria detected through the above-described procedure as any of the flags F 1  to F 15 . The relationship between scenario unit selection criteria and the flags F 1  to F 15  is shown in FIG.  4 . 
     First, in step S 202 , among the first scenario units a 1 , b 1 , and cl composing the scenarios SA, SB, and SC, respectively, the one that corresponds to the game decided in the above step S 4  is selected. Then, the procedure goes to a next step S 204 . 
     In step S 204 , among the second scenario units a 2 , b 2 , and c 2  composing the scenarios SA, SB, and SC, respectively, the one that corresponds to the first scenario unit selected in step S 202  is selected. Then, the procedure goes to a next step S 206 . 
     In step S 206 , it is decided whether the flag F 1  has been set. If the flag F 1  has been set, that is, if the game A is played for the first time, the procedure goes to step S 208 . 
     In step S 208 , the scenario unit a 3  is selected as the third scenario unit composing the scenario SAα. Then, the procedure goes to step S 262 . On the other hand, if No in step S 206 , the procedure goes to step S 210 . 
     In step S 210 , it is decided whether the flag F 2  has been set. If the flag F 2  has been set, that is, if the game B is played for the first time, the procedure goes to step S 212 . 
     In step S 212 , the scenario unit b 3  is selected as the third scenario unit composing the scenario SBα. Then, the procedure goes to step S 262 . On the other hand, if No in step S 210 , the procedure goes to step S 214 . 
     In step S 214 , it is decided whether the flag F 3  has been set. If the flag F 3  has been set, that is, if the game C is played for the first time, the procedure goes to step S 216 . 
     In step S 216 , the scenario unit c 3  is selected as the third scenario unit composing the scenario SCα. Then, the procedure goes to step S 262 . On the other hand, if No in step S 214 , the procedure goes to step S 218 . 
     In step S 218 , it is decided whether the flag F 4  has been set. If the flag F 4  has been set, that is, if only the game A has been cleared at the time of starting the game B, the procedure goes to step S 220 . 
     In step S 220 , the scenario unit b 4  is selected as the third scenario unit composing the scenario SBβ. Then, the procedure goes to step S 262 . On the other hand, if No in step S 218 , the procedure goes to step S 222 . 
     In step S 222 , it is decided whether the flag F 5  has been set. If the flag F 5  has been set, that is, if only the game A has been cleared at the time of starting the game C, the procedure goes to step S 224 . 
     In step S 224 , the scenario unit c 4  is selected as the third scenario unit composing the scenario SCβ. Then, the procedure goes to step S 262 . On the other hand, if No in step S 222 , the procedure goes to step S 226 . 
     In step S 226 , it is decided whether the flag F 6  has been set. If the flag F 6  has been set, that is, if only the game B has been cleared at the time of starting the game A, the procedure goes to step S 228 . 
     In step S 228 , the scenario unit a 4  is selected as the third scenario unit composing the scenario SAβ. Then, the procedure goes to step S 262 . On the other hand, if No in step S 226 , the procedure goes to step S 230 . 
     In step S 230 , it is decided whether the flag F 7  has been set. If the flag F 7  has been set, that is, if only the game B has been cleared at the time of starting the game C, the procedure goes to step S 232 . 
     In step S 232 , the scenario unit c 5  is selected as the third scenario unit composing the scenario SCγ. Then, the procedure goes to step S 262 . 
     On the other hand, if No in step S 230 , the procedure goes to step S 234  shown in FIG.  10 . 
     In step S 234 , it is decided whether the flag F 8  has been set. If the flag F 8  has been set, that is, if only the game C has been cleared at the time of starting the game A, the procedure goes to step S 236 . 
     In step S 236 , the scenario unit a 5  is selected as the third scenario unit composing the scenario SAγ. Then, the procedure goes to step S 262 . On the other hand, if No in step S 234 , the procedure goes to step S 238 . 
     In step S 238 , it is decided whether the flag F 9  has been set. If the flag F 9  has been set, that is, if only the game C has been cleared at the time of starting the game B, the procedure goes to step S 240 . 
     In step S 240 , the scenario unit b 5  is selected as the third scenario unit composing the scenario SBγ. Then, the procedure goes to step S 262 . On the other hand, if No in step S 238 , the procedure goes to step S 242 . 
     In step S 242 , it is decided whether the flag F 10  has been set. If the flag F 10  has been set, that is, if the game A and then the game B have been cleared at the time of starting the game C, the procedure goes to step S 244 . 
     In step S 244 , the scenario unit c 6  is selected as the third scenario unit composing the scenario SCδ. Then, the procedure goes to step S 262 . On the other hand, if No in step S 242 , the procedure goes to step S 246 . 
     In step S 246 , it is decided whether the flag F 11 . Has been set. If the flag F 11  has been set, that is, if the game B and then the game A have been cleared at the time of starting the game C, the procedure goes to step S 248 . 
     In step S 248 , the scenario unit c 7  is selected as the third scenario unit composing the scenario SCε. Then, the procedure goes to step S 262 . On the other hand, if No in step S 246 , the procedure goes to step S 250 . 
     In step S 250 , it is decided whether the flag F 12  has been set. If the flag F 12  has been set, that is, if the game A and then the game C have been cleared at the time of starting the game B, the procedure goes to step S 252 . 
     In step S 252 , the scenario unit b 6  is selected as the third scenario unit composing the scenario SBδ. Then, the procedure goes to step S 262 . On the other hand, if No in step S 250 , the procedure goes to step S 254 . 
     In step S 254 , it is decided whether the flag F 13  has been set. If the flag F 13  has been set, that is, if the game C and then the game A have been cleared at the time of starting the game B, the procedure goes to step S 256 . 
     In step S 256 , the scenario unit b 7  is selected as the third scenario unit composing the scenario SBε. Then, the procedure goes to step S 262 . 
     On the other hand, if No in step S 254 , the procedure goes to step S 258 . 
     In step S 258 , it is decided whether the flag F 14  has been set. If the flag F 14  has been set, that is, if the game B and then the game C have been cleared at the time of starting the game A, the procedure goes to step S 260 . 
     In step S 260 , the scenario unit a 6  is selected as the third scenario unit composing the scenario SAδ. Then, the procedure goes to step S 262 . 
     On the other hand, if No in step S 258 , the flag F 15  has been set. That is, the game C and then the game B have been cleared at the time of starting the game A. Therefore, the scenario unit a 7  is selected as the third scenario unit composing the scenario SAε. Then, the procedure goes to step S 262 . 
     In step S 262 , among the fourth scenario units a 8 , b 8 , and c 8  composing the scenarios SA, SB, and SC, respectively, the one that corresponds to the game decided in the above step  34  as selected is selected. 
     As described above, in the check-at-start subroutine in step # 100  described with reference to FIGS. 6,  7 , and  8 , the interrelation between the games A, B, and C is detected. Then, the detected interrelation is represented as any one of the flags F 1  to F 15 . Based on which flag has been set, the combination of scenario units composing each of the game scenarios SA, SB, and SC is varied. Therefore, for example, five scenarios SAα, SAβ, SAγ, SAδ, and SAε can be generated for the game A, thereby achieving versatility in game content. As evident from the above, the same goes for the games B and C. 
     Also in the embodiment of the present invention, each of the progressions of the games A, B, and C and the interrelation therebetween are typically applied as the scenario unit selection criteria, as shown in FIGS. 3 and 4. Alternatively, as such scenario unit selection criteria, a time taken for clearing each scenario unit composing a single scenario may be applied for selecting the following scenario unit. 
     Furthermore, the number of strokes of a specific or arbitrary key operated by the player by the time he/she clears a single scenario unit or during a predetermined time may be applied for the purpose of selecting the following scenario unit. 
     Also, information about time kept by an internal clock incorporated in the game processor GP may be applied for the same purpose. As such, by applying the amount varied irrespectively of the player&#39;s operation as the criteria for scenario unit selection, versatility in a single game can be achieved. If an amount that is difficult to be recognized by the player is used, the game content will become more unpredictable. 
     In the above-described embodiment, the game program and backup data are stored in a single game cassette. Alternatively, the backup data may be separately stored in a memory card such as a RAM card, or in a storage unit such as RAM or a hard disk internally provided in the game machine. 
     Moreover, the game program may be stored in a disk-like storage medium detachably inserted in the game machine, such as an optical disk or a magnetic disk. 
     While the invention has been described in detail, the foregoing description is in all aspects illustrative and not restrictive. It is understood that numerous other modifications and variations can be devised without departing from the scope of the invention.