Abstract:
Disclosed herein is a game played on a gaming device that displays a randomly selected array of symbols, where the symbols across one or more paylines are evaluated by circuitry to determine an award to be granted. A trigger event, such as the occurrence of a certain plurality of special symbols, initiates a series of free games. The number of free games and an award multiplier associated with each free game are dependent on the particular type of special symbols making up the trigger event.

Description:
FIELD OF THE INVENTION 
       [0001]    This invention relates to gaming devices, such as slot machines, and, in particular, to additional features performed in a game that grants awards to a player based upon displayed symbols. 
       BACKGROUND 
       [0002]    Common slot machines randomly select and display an array of symbols on a video screen, then grant an award to a player based on the occurrence of certain symbol combinations across paylines. Typically, the game ends after the symbols are displayed and the award, if any, is granted. Although these types of games are highly successful, it is advantageous to provide an additional feature to this basic game to make the game more interesting to a player. A more interesting game will generate increased revenue to the casino by its increased play. 
       SUMMARY 
       [0003]    Disclosed herein is a game played on a gaming device that displays a randomly selected array of symbols, such as a video slot machine, and electro-mechanical slot machine, or a video monitor connected to a computer for on-line gaming. In one embodiment, the array is 5×3 symbol positions. The combinations of symbols across one or more activated paylines are evaluated by a processor to determine an award to be granted. The present invention adds an additional feature to this conventional operation of a gaming machine. 
         [0004]    In one embodiment of the present invention, a variety of special symbols are disposed around actual or virtual reels. A certain combination of the special symbols, such as three or more of the special symbols being displayed, causes each of the special symbols to award an associated number of free games, with any awards during the free games multiplied by an associated multiplier. For example, the special symbols may be $1, $2, $3, $4, and $5. Upon a combination of, for example, the special symbols $1, $2, and $4 being displayed on the screen after the reels have been rotated and randomly stopped, the player wins 5 free games with a ×1 multiplier for the $1 symbol, 5 free games with a ×2 multiplier for the $2 symbol, and 3 free games with a ×5 multiplier for the $4 symbol. The free games associated with each multiplier are then played in sequence until all 13 free games are played. 
         [0005]    In one embodiment, during the free games, additional free games may be awarded upon the occurrence of a trigger event. The trigger event may be one or more special symbols occurring during the free games, rather than the three or more special symbols needed for the trigger event during the base game, to increase the chances that the player will win more free games during play of a free game. 
         [0006]    The number of free games and the multiplier may be any number for a particular special symbol. Although in the above example, the special symbols were scatter symbols (i.e., payline does not matter), the trigger event that initiates the special feature may require the special symbols to occur across a single payline. 
         [0007]    Other variations are described. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0008]      FIG. 1  illustrates a gaming machine prior to a first spin, where the machine has two screens, where one screen displays a 5×3 array of symbols and the other screen provides information about the special feature, in accordance with one embodiment of the present invention. 
           [0009]      FIG. 2  illustrates the machine of  FIG. 1  after the first spin, where the machine displays a trigger event (three or more special symbols ($X) in the base game. 
           [0010]      FIG. 3  illustrates the machine of  FIG. 2 , where the top screen displays the number of free games the player has just won and the associated award multipliers during the free games. 
           [0011]      FIG. 4  illustrates the machine of  FIG. 3  after the first free game is played, where the top screen displays the status of the free games. 
           [0012]      FIG. 5  is a flowchart of a method in accordance with one embodiment of the invention. 
           [0013]      FIG. 6  is a block diagram of the main components in the gaming machine of  FIG. 1 . 
       
    
    
     DETAILED DESCRIPTION 
       [0014]    The invention can typically be implemented by installing a software program in a modern video or electro-mechanical gaming machine. 
         [0015]      FIG. 1  is a simplified front view of a video slot machine  10 . Many other types of platforms may be used instead to implement the invention. The slot machine  10  has an upper video screen  12  and a lower video screen  14 . Each screen may be a thin film transistor (TFT) display, a liquid crystal display (LCD), a cathode ray tube (CRT), or any other type of display. In another embodiment, a single screen displays all the information needed to play the game. 
         [0016]    A coin slot  16  receives coins or tokens, and a bill slot  18  receives bills or coupons. A separate slot may dispense payment coupons for cashless gaming, and/or a coin tray (not shown) may receive coins upon the player cashing out via a coin hopper. 
         [0017]    Prior to cashing out, awards are typically granted to the player by incrementing a credit counter  20 . Control buttons  22  allow the player to spin the simulated reels, make bets, cash out, or enter other conventional instructions. 
         [0018]    One example of the game will be described with respect to the figures. 
         [0019]    In  FIG. 1 , the player has inserted a bet or has credits remaining. The credit meter  20  shows that the player has 10 credits to play the game. The lower screen  14  depicts five simulated reels 1-5 forming five columns and three rows of symbols to create a 5×3 array of symbols. The 5×3 array shows the symbols A-O from a previous game, where the player did not obtain a trigger event for initiating the inventive feature. In the example, it is assumed that the trigger event is the occurrence of three or more special symbols anywhere in the display. The special symbols are $1, $2, $3, $4, and $5. Randomly selecting the symbol array on the lower screen  14  is referred to as the base game. 
         [0020]    In one embodiment, each virtual reel has only one type of special symbol (e.g., reel 1 only contains the $1 symbol, etc.). In another embodiment, a reel may have more than one type of special symbol. 
         [0021]    Although symbols A-O are used for simplicity, standard symbols include fruit symbols and symbols associated with the theme of the particular slot machine. The special symbols may be different color diamond symbols or other types of symbols. The particular icons used are not important. For amusement, each vertical column of symbols is scrolled to emulate a motor-driven reel, and each of the virtual reels is typically stopped in sequence after a few seconds to reveal the final 5×3 array of symbols. 
         [0022]    The upper screen  12  may have any purpose and is optional. In the example, the upper screen is used to explain the features to the player and helps the player keep track of free games she has won. The upper screen  12  may also show all the available winning symbol combinations and the awards as a static display and then show the features once the trigger event occurs. A display glass may also show the winning symbol combinations and awards. 
         [0023]    After the player makes the bet (assume 10 credits) and optionally selects paylines using the control buttons  22 , the five reels spin and randomly stop. Although a pseudorandom algorithm is typically used in gaming machines, the term “random” is used herein to mean either pseudorandom or random. 
         [0024]      FIG. 2  illustrates the new 5×3 array of symbols that results from the stopped reels. The player is granted an award for any winning symbol combinations in the base game prior to any feature game occurring. A trigger event occurred in  FIG. 2  since more than three special symbols are displayed. The special symbols are scatter symbols, which means they do not have to be on the same payline to be effective. The special symbols appearing on the screen are sensed by a microprocessor in the slot machine, and the microprocessor initiates the free games. 
         [0025]      FIG. 3  illustrates how the upper screen  12  is used to display the free game rules and what free games the player has won. Any form of presentation of the awarding of the free games, such as animation, may be suitable. In the present example, assuming the trigger event has occurred, the display of a $1 symbol awards the player 5 free games and any award is multiplied by 1; the display of a $2 symbol awards the player 5 free games and any award is multiplied by 2; the display of a $3 symbol awards the player 5 free games and any award is multiplied by 3; the display of a $4 symbol awards the player 3 free games and any award is multiplied by 5; and the display of a $5 symbol awards the player 3 free games and any award is multiplied by 10. Any number of free games and multipliers may be associated with the special symbols. Typically, the multiplier is based on the likelihood that the particular special symbol will occur in a display, where the lowest likelihood special symbol has the highest multiplier. The winning symbol combinations during the free games may be the same as or different from the winning symbol combinations during the base game. 
         [0026]    Since the player obtained the special symbols $1, $2, $3, $4, and $5 in the example of  FIG. 2 , the player gets 21 free games with various award multipliers. Each of the special symbols involved in the trigger event grants the player the free games and multiplier associated with that special symbol. For example, had only three $1 symbols been the trigger event, the player would receive 15 free games with a ×1 multiplier. 
         [0027]    The player then plays the free games by pressing the spin-reels button (one of control buttons  22 ) or pulling a handle. The bet and active paylines applied to the free games will typically be the same as those used for the base game. This encourages the player to play the maximum bet in the base game. 
         [0028]    The free games are played in sequence, starting with the free games with the lowest multiplier so the player&#39;s excitement level builds to the higher multiplier games. 
         [0029]    In another embodiment, the free games are played in another sequence, such as in the order that the special symbols appeared in the reel display. 
         [0030]      FIG. 4  shows the display after the first free game is played. Assuming the player wins 30 credits for the four L&#39;s across the center payline, this win increments the credit counter  20  by 30. This win is not multiplied since the free spin is a result of the $1 symbol being part of the trigger event, which provides no multiplier. During free games having a multiplier greater than 1, any award is multiplied by that multiplier. 
         [0031]    Illustrating subsequent free game examples is not necessary to fully understand the invention. 
         [0032]      FIG. 5  is a flowchart of the basic steps in one embodiment of the invention. In step  31 , the player makes a bet and spins the reels. 
         [0033]    In step  32 , an array of symbols is displayed in the base game. 
         [0034]    In step  33 , any awards are paid for winning symbol combinations across activated paylines. 
         [0035]    In step  34 , it is determined by the machine&#39;s microprocessor whether a trigger event has occurred. If not, the game is over. 
         [0036]    If a trigger event has occurred, in step  35 , the microprocessor determines the sequence of free games to be played and the award multipliers. 
         [0037]    In step  36 , any award generated for winning symbol combinations in a free game is multiplied by the associated multiplier. In another embodiment, some of the symbols in the free game automatically generate an award without the symbol being part of a winning combination, and such an award is multiplied by the award multiplier. 
         [0038]    In step  37 , the microprocessor determines whether a trigger event occurred during the free game. If a number of special symbols occurred during the free games, such special symbols award additional free games along with award multipliers. These additional free games may be played at the end of the other free games or in any other sequence. In one embodiment, only one special symbol is needed to be displayed during the free games in order to win additional free games. Thus, the likelihood of obtaining a trigger event is increased during the free games. 
         [0039]    If no trigger event occurred in step  37 , the free game sequence is continued. If a trigger event occurred in step  37 , additional free games are won in step  38 . 
         [0040]      FIG. 6  illustrates basic circuit blocks in a suitable gaming device. A control unit (CPU  40 ) runs a gaming program (including the invention) stored in a program ROM  43 . The program ROM  43  may include a pseudorandom number generator program for selecting symbols and for making other random selections. A coin/credit detector  41  is sensed by the CPU  40  to determine if there are sufficient credits to play the game. A pay table ROM  44  detects the outcome of the game and identifies awards to be paid to the player. A payout device  42  pays out an award to the player in the form of coins upon termination of the game or upon the player cashing out. The payout may also be in the form of a coded paper ticket, credits on a smart card or magnetic strip card, or in any other form. A display controller  45  receives commands from the CPU  42  and generates signals for the various displays  46 . If a display  46  is a touch screen, player commands may be input through the display screen into the CPU  40 . 
         [0041]    Instead of the gaming machine being a video gaming machine, the machine may use stepper-motor driven reels to select and display the symbol array. Such reel-type machines are processor controlled, and the reels simply display an array of symbols that have already been predetermined by the processor. The machine may display the free game information on a video screen and used motor driven reels to display the symbols. The machine may also be a player&#39;s home computer where the player plays via the Internet. 
         [0042]    While particular embodiments of the present invention have been shown and described, it will be obvious to those skilled in the art that changes and modifications may be made without departing from this invention in its broader aspects and, therefore, the appended claims are to encompass within their scope all such changes and modifications as fall within the true spirit and scope of this invention.