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United States Patent Application 
20010009865

Kind Code

A1

DEMAR, LAWRENCE E.
; et al.

July 26, 2001

GAMING MACHINE WITH BONUS MODE
Abstract
A gaming machine is operated by a programmed microprocessor in which the
first mode of operation, a basic gambling game, is implemented such as
video poker or reeltype slot machine play. If bonus symbols are selected
in the basic mode, a bonus mode is triggered. In the bonus mode the same
or a different game is implemented by the microprocessor system
employing a Bernoulli trial procedure in which the player continues to
play and receive awards until a losing combination occurs. The hit rate
for the bonus mode is greater than 50% although the overall hold
percentage of the game remains below 100%.
Inventors: 
DEMAR, LAWRENCE E.; (WINNETKA, IL)
; FROHM, ERICA; (EVANSTON, IL)

Correspondence Address:

WILLIAM T RIFKIN
RUDNICK AND WOLFE
203 NORTH LASALLE STREET
CHICAGO
IL
606011293

Serial No.:

835840 
Series Code:

08

Filed:

April 23, 1997 
Current U.S. Class: 
463/20 
Class at Publication: 
463/20 
International Class: 
A63F 009/24 
Claims
What is claimed is:
1. A processor controlled game of chance comprising: a) a processor,
operating according to a game program, for randomly selecting symbols and
for awarding credits when winning symbol combinations are selected; b)
display means on which said selected symbol combinations are displayed to
a game player; c) said processor operating in a basic mode unless and
until a symbol combination, designated as a bonus combination in said
game program, is selected, said processor, in said basic mode, selecting
symbols and awarding credits or money in response to the input of money
or credits by said player; d) said processor operating in a bonus mode
after said bonus combination is selected, said processor, in said bonus
mode: (1) selecting symbol combinations as a sequence of Bernoulli
trials; (2) displaying the symbol combinations for each trial; (3)
awarding credits for winning combinations associated with each trial
until a losing combination is selected, said bonus mode having a hit rate
for winning combinations in excess of fifty percent; whereby a player who
reaches the bonus mode accumulates credits as a function of the number of
Bernoulli trials survived.
2. In a gaming machine including processor means for randomly selecting
outcomes, some of which are winners and the remainder being losers; and
for awarding credits or money corresponding to said winners, and display
means for displaying the selected outcomes the improvement comprising: a)
said processor means being programmed to designate certain outcomes as a
bonus event permitting the play of a bonus game; b) said processor,
during bonus game play, iteratively and randomly selecting outcomes as a
sequence of Bernoulli trials, displaying said outcomes and awarding the
credits associated therewith until a losing outcome is selected, said
bonus game having a hit rate for winning combinations in excess of fifty
percent; whereby a player who reaches the bonus game accumulates credits
as a function of the number of Bernoulli trials survived.
3. A method of operating a gaming machine having a processor for randomly
selecting game outcomes and for awarding credits or money for winning
outcomes and, a display for displaying said outcomes to a game player
comprising the steps of: a) operating said processor in a basic mode
unless and until an outcome, designated as a bonus event, is selected,
said basic mode permitting outcome selection, display and credit awards
only in response to the input of a credit by said player; b) operating
said processor in a bonus mode after said bonus event is selected, said
bonus mode operation causing: (1) random selection and display of
outcomes as a sequence of Bernoulli trials which continue until a losing
trial occurs; (2) the award of credits or money for winning outcomes for
each trial, said bonus mode having a hit rate for winning outcomes in
excess of fifty percent; whereby a player who reaches the bonus mode
accumulates credits as a function of the number of Bernoulli trials
survived.
4. The device of claim 1 wherein said processor is programmed to select
poker symbols for the basic mode game.
5. The device of claim 1 wherein said processor is programmed to select
poker symbols for the bonus mode game.
6. The device of claim 1 wherein the display means includes a video
display on which the symbols are displayed for the basic game.
7. The device of claim 1 wherein the display means includes a video
display on which the symbols are displayed for the bonus game.
8. The device of claim 1 wherein the display means includes at least two
physical reels having symbols arranged thereon, the selected symbols
being displayed to a player by rotation of said reels.
9. The device of claim 8 wherein said reels are used as the display for
the basic game.
10. The device of claim 8 wherein said reels are used as the display for
the bonus game.
11. The device of claim 1 wherein said display means includes: (a) a reel
type display on which selected symbols are displayed to a player by
rotation of said reels; and (b) a video display on which symbols may
appear; one of said displays being used for said basic game, the other
being used for the bonus game.
12. The device of claim 1 wherein said processor is programmed to produce
an expected value (EV) for said bonus mode greater than 1.0 but wherein
the EV of the combined basic and bonus modes is less than 1.0.
13. The device of claim 2 wherein said processor is programmed to produce
an expected value (EV) for said bonus mode greater than 1.0 but wherein
the EV of the combined basic and bonus modes is less than 1.0.
14. The method of claim 3 wherein said processor is programmed to produce
an expected value (EV) for said bonus mode greater than 1.0 but wherein
the EV of the combined basic and bonus modes is less than 1.0.
15. In a gaming machine including processor means for randomly selecting
outcomes, some of which are winners and the remainder being losers; and
for awarding credits or money corresponding to said winners, and display
means for displaying the selected outcomes the improvement comprising: a)
said processor means being programmed to designate certain outcomes as a
bonus event permitting the play of a bonus game; b) said processor,
during bonus game play, iteratively and randomly selecting outcomes each
of which is a Bernoulli trial, but wherein p, the probability of success
may vary; c) displaying said outcomes and awarding the credits associated
therewith until a losing outcome is selected, said bonus game having a
hit rate for winning combinations in excess of fifty percent; whereby a
player who reaches the bonus game accumulates credits as a function of
the number of Bernoulli trials survived.
16. The device of claim 15 wherein said processor initiates a consolation
trial if the first Bernoulli trial during bonus game play results in a
losing outcome, said consolation trial awarding a randomly determined
number of credits as a consolation prize.
17. The method of claim 3 further including the step of: c) initiating a
consolation trial if the first Bernoulli trial during bonus game play
results in a losing outcome, said consolation trial awarding a randomly
determined number of credits as a consolation prize.
Description
BACKGROUND OF THE INVENTION
[0001] This invention relates to gaming machines. More specifically, it
relates to gaming machines of the type used in casinos. Such devices
include the familiar spinning reel slot machine, video slot machines,
video display poker games and the like. Spinning reel slot machines have
maintained their popularity evolving from electromechanical devices to
the present day devices which employ microprocessor control. In modern
devices the spinning reels are used merely as a display to advise a
player if he has won or lost a game of chance played entirely in computer
memory according to the rules embedded in a computer program. Video
display type gaming machines are similar in terms of their computer
program and operation but, in place of spinning reels, a CRT or dot
matrix display is provided upon which a simulation of a desired game is
presented. For example a poker game, a spinning reel slot machine, a
black jack game or other casino game may be simulated on the display.
Whether the gaming machine uses spinning reels, a CRT display or some
other manner of informing the player of game outcomes, it is necessary
that the casino owner make a profit. To that end the game will be
percentaged so that some portion of the revenue played into the machine
is retained as profit. Thus for every dollar played, on average, a
typical gaming machine will retain (hold) between 1% and 25%.
[0002] With the constraint that there must be a positive hold percentage
comes the problem of offering higher awards to induce players to use the
equipment. In reel spinning slot machines this has been a formidable
problem because the possible outcomes are normally related to the number
of stop positions per spinning reel. Thus, in the case of three reels
each having 20 stop positions thereon, the probability of any
threesymbol combination occurring is one in eight thousand. This
provides an upper limit on the amount that may be paid out if a profit is
to be made. In an effort to overcome this limitation microprocessor
based machines have been developed. The game is played in the
microprocessor system and the reels are used merely to display the
results. Much greater odds may be employed than permitted by the reel
strip size thereby increasing the possible payouts by decreasing the
chances that a winning combination will occur.
[0003] U.S. Pat. No. 4,448,419 to Telnaes provides one solution to this
problem. It is desired, however, according to the present invention, to
provide a more universal solution which pays high awards while at the
same time increasing player enjoyment. The present invention is suitable
for implementation in a reeltype slot machine design as will be
explained in the description of a preferred embodiment. However, it may
also be implemented strictly as a video game, without the use of spinning
reels, or it may be used for other types of games or for combinations of
games. All that is required is that there be a standard type base game
which has a hold percentage built into its table of payouts. In addition,
the base game must include a special symbol combination or similar
mechanism by which a lucky player can qualify to play a bonus game. The
bonus game may be similar to the base game, albeit with different symbol
probabilities or it may be a completely separate game on the same or a
different display. Thus for example, in a preferred embodiment a reel
spinning slot machine is used for the base game while a dot matrix
display simulation of a slot machine or card game is used for the bonus
game. The pay tables for the basic and bonus games must be mathematically
combined such that there is still a positive hold percentage, which
represents the profit for the casino establishment. Other combinations of
games are clearly suitable for use with the present invention such as a
reel spinning slot machine in which the basic game uses a first set of
symbol probabilities and the bonus game uses a second set of symbol
probabilities. Another possibility is a video poker game for the base
game and wherein the bonus game could be a video slot game, or another
poker game with a different pay table.
[0004] A principal feature of the present invention is the structure of
the bonus game. A player must play the base game until he qualifies for
the bonus game. Qualification is a low frequency event. The bonus game
however is a high hit rate game in which the player is expected to win
several times in a row and wherein the player is permitted to keep
playing and collect his winnings (with or, optionally, without payment of
additional coins by the player) until he loses. In the context of a
reeltype slot machine, this may be referred to as a "spin 'til you lose"
bonus game. It is believed that the thrill and excitement of a bonus game
in which a player's probability of winning is significantly greater than
50% and in which he keeps playing until he loses, all the while
collecting payouts, will add a new and significantly greater level of
player excitement.
[0005] It is accordingly an object of the present invention to provide a
gaming machine in which there is a basic game and a bonus game and
wherein the bonus game has a playuntilyoulosemode in which the
probability of winning each trial in the bonus game is greater than 50%.
[0006] It is another object of the invention to provide a combination
gaming machine having basic and bonus modes wherein the basic mode
occasionally initiates the bonus mode game which is a high hitrate game
in which the player may continue to play until he loses.
[0007] It is a further object of the invention to provide a dual mode
gaming machine in which a bonus mode has a hit rate of greater than 50%
and which is based upon a series of Bernoulli trials which continue until
the player loses.
[0008] These and other objects of the invention will be apparent from the
remaining portion of this specification.
BRIEF DESCRIPTION OF THE DRAWINGS
[0009] FIG. 1 is a simplified illustration of a spinning reel slot machine
having a dot matrix display suitable for use with a bonus mode according
to the present invention.
[0010] FIG. 1A is an enlargement of the slot machine display showing how
symbols appear on, above and below the payline.
[0011] FIG. 2 is a symbol table for a 22 symbol reeltype slot machine
augmented to include bonus symbols (WinStreak) and special blanks
(WSBlank) immediately adjacent to the bonus symbols.
[0012] FIG. 2A is a math table combining the expected value calculation
for the base and bonus games according to an embodiment of the invention.
[0013] FIG. 2B is a set of reel strips for the symbol table of FIG. 2 for
a base game.
[0014] FIG. 3 is a combined symbol and math table for the bonus game
according to an embodiment of the invention.
[0015] FIG. 3a is a pay table for both the base and bonus games.
[0016] FIGS. 4 and 5 are software flow diagrams illustrating how the
invention may be implemented.
[0017] FIG. 6 is a graph of the Geometric function for Bernoulli trials
according to an example of the invention.
[0018] FIG. 7 is a consolation table for an optional feature of the
invention.
DETAILED DESCRIPTION
[0019] As indicated in the background portion of this specification, the
present invention can be implemented using almost any type of gaming
device. The game is divided into two parts: a basic game and bonus game.
The basic game can be any type of game of chance. Typically it will be a
spinning reel slot machine, a video poker game or similar type of game
suitable for wagering. In the basic game, some event, or sequence of
outcomes which occur at a low frequency permits the playing of the bonus
game. The bonus game is another game of chance with a very high hit rate
(i.e., the probability that a player will win rather than lose). The hit
rate in the bonus game, according to the present invention, should be
greater than 50% and is most effective when selected to be greater than
70%. When a trigger event occurs in the base game, play switches to the
bonus game. Preferably, play of the bonus game results in a series of
free trials i.e., not requiring the game player to insert any additional
coins or credits into the machine. Alternately, however, the bonus game
can be played by requiring coins or credits with the player knowing that
his chance of winning has been significantly increased. If a bonus game
trial results in a win, then the player receives the amount associated
with that particular win and another play or trial occurs. Trials
continue in the bonus game until a losing trial occurs.
[0020] As indicated previously, the basic game and bonus game may be the
same game system with different pay tables and rules. For example, a
video poker game could be the base game where a particular hand, such as
fourofakind is required to trigger operation of the bonus game. The
bonus game however, although the same video poker game, would have a more
favorable pay table offering a much higher hit rate. This could also be
accomplished by the use of wild cards or other changes to the game rules.
[0021] It is also contemplated that the base game and bonus game could be
executed on the reels of a spinning reel slot machine where the symbols
on the reels are given two different sets of probabilities for the base
and bonus games. Another alternative is for the two games to be very
different, such as a spinning reel slot machine for the base game coupled
with a video poker game as the bonus game. It is also contemplated, and
disclosed herein as one preferred embodiment, to use a spinning reel slot
machine as the base game and a video display type slot machine simulation
as the bonus game.
[0022] Thus, referring to FIG. 1, there is shown a simplified diagram of a
reeltype slot machine. The machine 10 includes a display window 12
through which a player may observe three spinning reels, 14, 16 and 18.
Game play is initiated by inserting a coin or playing a credit and then
pulling the lever 20 or operating a push button switch for the same
purpose. A microprocessor then operates according to its game program
randomly selecting a reel stop position for each of reels 14, 16 and 18.
The reels are set in motion to give the player the feeling of randomness,
but in due course the reels are stopped at the preselected stop positions
using technology well known in this art which typically includes stepper
motors for driving the reels and stopping them at the desired position
under processor control. A payline 22 is located centrally of the display
12. Symbols which stop on the payline are evaluated to determine if a
winning combination has occurred. If so, in a typical slot machine, a
payout is made and the game is over. In some games the symbols above and
below the payline are also visible in the display window. This provides
additional excitement to the player. In some games, the ability to see
the next symbol, above and below the payline, can be used to provide
additional entertainment and payoff features. Thus, for example as shown
in FIG. 1A, which is an enlargement of the display window 12, three
symbols are visible on Reel 14. Symbol A is on the payline, while symbol
B is above the payline and symbol C is below the payline. The present
invention makes use of this feature of traditional slot machines in a
manner to be explained hereafter. With reference to the programming and
operation of processor controlled slot machines, the reader is directed
to the disclosures in the following U.S. Pat. No. 4,095,795 to Saxton and
U.S. Pat. No. 5,456,465 to Durham which are hereby incorporated by
reference.
DESCRIPTION OF A PREFERRED EMBODIMENT
[0023] Returning to FIG. 1, according to a preferred embodiment of the
invention, the slot machine 10 is provided with a videotype display 32
which may be a CRT or a dot matrix display, as desired. The display is
housed in a vertically disposed enclosure secured to the upper portion of
the slot machine 10. The display 32 is used for purposes of playing a
bonus game. If the bonus game is a poker game for example, a poker hand
would be shown on the display and the player paid if a winning hand
occurs. Similarly, if the bonus game is a slot machine simulation,
spinning symbols would be simulated on the display stopped in various
combinations, some of which would constitute winners.
[0024] There will now be described one embodiment of the invention, which
is currently preferred, for implementing the game in a commercial
environment. It must be reiterated that this is only one such possibility
and that any combination of two suitable games that are percentaged and
interoperable according to the present invention may be used. The basic
game is played on the spinning reels of the slot machine 10, while the
bonus game is played on the dot matrix display 32. The basic game has
typical symbols such as Cherry, Single Bar, Double Bar and Triple Bar
spaced on the reel strips 14, 16 and 18. Typically these symbols will be
randomly displayed on the reel strips, usually separated by a blank,
which is itself a symbol. In addition to these standard slot machine
symbols, the reel strips also carry a bonus symbol, the selection of
which leads to operation of the bonus game as will be described.
[0025] FIG. 2 is a table illustrating the reel strip symbol frequency for
the base game. The symbols which appear on Reel 1 include: the WinStreak
or bonus symbol, the "special" WinStreak blanks on either side of the
WinStreak bonus symbol, the 3Bar, 2Bar and 1Bar symbols plus regular
blanks and cherries for a total of 22 symbols one at each of 22 reel stop
positions. Reels 2 and 3 are similar. A typical symbol layout for this
example is shown in FIG. 2b. The occurrence of the various symbols varies
from reel to reel, but each reel has but 22 symbols in all and therefore
the odds of any possible combination of distinct symbols appearing on the
payline is 1 in 10,648 (22.times.22.times.22). Thus, according to a
preferred implementation of the invention, the base game may be a
standard processor controlled spinning reel slot machine, augmented
however, with bonus symbols and special blanks. It is substantially
similar to the system described in U.S. Pat. No. 4,095,795 to Saxton,
albeit a different software algorithm is employed for selecting the
symbols.
[0026] As with most such games, the payout table is set so that the
machine retains a percentage of the money played (the hold percentage).
Calculation of the hold percentage of the machine however requires
inclusion of the bonus game. For illustrative purposes, a typical pay
schedule for the reel strips of FIG. 2 is shown in FIG. 2A. The schedule
includes the calculated payouts for the bonus game as will be discussed
hereafter. FIG. 2A also shows the probability of occurrence of winning
combinations and the expected value (EV) from which the hold percentage
is calculated. Thus for the reel strip of FIG. 2, the probability of 3
bars occurring is 0.000376 and since it pays 50 coins the EV is
(50.times.0.000376)=0.018783. By summing the EV's for all winning
combinations, including the bonus game combinations represented in the
schedule as "3WinStreak and "3AnyStreak", it can be determined that the
illustrated embodiment has a hold percentage of 94.4045. That is, for
every dollar played, on average, about 94 cents will be returned to the
player and 6 cents will be retained as profit.
[0027] In the basic game when three bonus symbols appear in the display 12
(either on the payline or above or below the payline) the bonus game is
initiated. If the three bonus symbols are on the payline, according to
the described embodiment, the bonus game is initiated with all awards
doubled. According to the preferred embodiment, the bonus game is
implemented in a dot matrix video display shown at 32 in FIG. 1. This
display is utilized by the processor to simulate a spinning reel slot
machine. The symbols used in the bonus game are Cherry, Single Bar,
Double Bar, Triple Bar, Blue 7 and Red 7. This is shown in the pay table
of FIG. 3. As will be apparent in this example, some symbols appear in
the bonus game which do not appear on the basic game reel strips. For
simplicity, it is preferable, but not necessary that the bonus game and
basic game use the same pay table for common symbols i.e., the same award
for 1 or 2 Cherries, and for Any Bar, Single Bar, Double Bar and Triple
Bar combinations. Typically posted on the outside of the machine is such
a combined pay table including the awards for the 3 Cherries, Any 7, Blue
7 and Red 7 which are only available in the bonus game.
[0028] In the illustrated implementation, there are 22 reel stop positions
on each of 3 reels of the basic game (See FIG. 2). The machine uses a
probability of 1 in 22 for each reel stop position on each reel. The
bonus symbols (WinStreak) appear two times (at two stop positions) on the
1st reel, three times on the 2nd reel and once on the 3rd reel. Thus, the
probability of 3 WinStreak symbols on the payline has a probability of
(2*3*1)/(22*22*22)=0.0005634861=A. This is the equal to 1 in 1774.667
spins. Preferably, the multiple instances of the WinStreak symbol on
reels 1 and 2 are placed at least 4 stop positions apart such as shown in
FIG. 2B. As a result, the blanks above and below the WinStreak symbols
will put a WinStreak bonus symbol within one position of the payline.
This provides 3 times the number of reel stop positions as there are
WinStreak Symbols which may trigger the bonus game. The probability of
entering the bonus game is (6*9*3)/(22*22*22)=0.0152141247=B. In summary,
a 2.times. multiplier bonus game (3 WinStreak symbols on the payline)
will be achieved with a probability of A. The probability of a regular
bonus round played with a 1.times. multiplier is BA.
[0029] A principal feature of the invention is the high hit rate of the
bonus game coupled with the spintilyoulose concept. The following
discussion of the bonus game mathematics will focus on a single coin
implementation. It is well known how to extend this to 2coin, 3coin,
5coin or other versions allowing more than one coin to be wagered on
each base game.
[0030] The expected return on a slot machine is computed by combining the
probability of each award with the amount of the award as indicated in
FIGS. 2 and 3. The expected value (EV) of each award is computed by
taking the product of the probability of achieving the award and the
number of coins awarded. The sum of each of these products results in the
expected return of the slot machine. This result will be in the form of a
fraction of 1 coin. The return of the combined game, (basic and bonus
games) according to the invention is computed by using this method for
each regular symbol combination of the base game, to which is added the
expected value of the bonus game combinations. The expected value of the
bonus game is computed by multiplying the probability of getting to the
bonus game by the expected number of coins awarded in the bonus game.
Call the expected value (EV) for coins won in the bonus game "C". The
value "C" is formed from two entries. Entry 1 is the probability of
playing the bonus round with a 1.times. multiplier BA from the preceding
discussion times the EV of the bonus game or ((BA)*C). Entry 2 is the
probability of playing the bonus round with a 2.times. multiplier (A),
times the EV of the bonus game times two or (A*C*2). To obtain the value
C requires additional information.
[0031] The expected value for each spin of the bonus game is computed in
the same manner described above, computing the sum of expected values for
each possible award. While any commercially successful slot machine must
have an expected value of less than 1.00 this restriction does not apply
to the bonus game per se. According to the present invention, as long as
the value C, when inserted into the expected value equation for the
entire game, results in a return for the entire game of less than 1.00,
the expected value for the bonus game may be greater than 1.00. The
expected coins per spin of the bonus game in the example is X coins. By
computing S, the expected number of spins until a loss occurs in the
bonus game, C is then computed as the product of this number of spins,
times the coins expected per spin, X. That is C=S*X.
[0032] According to the invention, the bonus game has a hit rate greater
than 50% and preferably greater than 70%. Assuming an 85% hit rate, for
example, on each spin the probability of losing is approximately 0.15.
The bonus game program is configured such that a player continues playing
until he loses. One of ordinary skill in probability theory will
recognize this mode of operation as a series of Bernoulli trials with
p=0.15. That is, a succession of trials (spins) each with a 0.15
probability of "success". Note that the probability expressed in a
Bernoulli trial is usually referred to as the "probability of success" of
that trial, but as applied to the bonus game the "success" of a trial
corresponds to losing the game (i.e. a nonwinning spin). For more
information on Bernoulli trials see, for example, Hogg and Tanis
"Probability and Statistical Inference" 4ed. pp. 150171, 1993
PrenticeHall Inc.
[0033] The function that shows the probability of "trials until success"
of a Bernoulli function (in this case the number of trials until we
achieve the 0.15 probability loss) is called the Geometric function (see
FIG. 6). This assumes p remains constant. It is permissible for p to vary
but the expected trials until success is more difficult to compute. The
probability of first success (loss on the bonus game after 1 trial) is
0.15. The probability of success (loss on the bonus game) after 2 trials
is 0.85*0.15=0.1275. For three trials, the calculation is
0.85*0.85*0.15=0.108375 and so on. It is well known that the expected
value (EV) of the Geometric function is 1/p where p is the probability of
"success" on a given trial (i.e. loss on the bonus game). Therefore, S
the expected number of spins of a bonus game with a hit rate of 85% is
1/0.15=6.667. Note this includes the final losing turn. The expected
value (C) for this bonus game may be computed by multiplying the value of
S (6.667) by the expected return per spin (X). That is C=S*X.
[0034] In practice, it is desirable to vary the payout percentages
slightly. Accordingly, the bonus game may be modified to have either a
different hit rate or a different average coins per spin value by
adjusting the symbol probabilities stored in the computer program. FIG. 3
is an example of such an adjusted pay table. For the example of FIG. 3,
the value X, the expected return per spin is 4.1751 (the sum of the EV
column) while the hit rate is 84.41% producing a value of S=6.4145. Thus
C=6.4145*4.175=26.781.
[0035] Referring to FIG. 2A the computed values C and 2C (for the 2.times.
multiplier feature) appear in the pay column as the first two entries and
are included in the EV column computations which sum to a 94.4045% hold.
Thus the expected win for the bonus game is combined with the expected
win of the base game to determine the expected value of the combined
game. Note that the pay column uses a value of C=27.733 rather than
26.780. This is due to the use of the consolation feature described in
connection with FIGS. 5 and 7.
[0036] From the foregoing, it will be understood that the present
invention provides a bonus game based on Bernoulli trials in which a
player, who qualifies by playing the base game, can play the bonus game
on a spintilyoulose basis. The bonus game has a hit rate of greater
than 50%, preferably higher than 70%. As a result, the player has a
strong inducement to "endure" the base game in order to qualify for bonus
game play in which he is statistically likely of winning several times in
a row and collecting relatively large payouts, while still returning a
profit for the casino establishment.
[0037] By providing a two stage gaming process in which a traditional game
of chance is played as the base game, the existing concept with which
players are familiar and comfortable is retained. At the same time,
however, a significantly more exciting feature is added in the form of a
bonus game. The software implementation of the invention, according to
the described embodiment, is relatively straightforward and will be
easily understood by those skilled in the art. As the specific
programming is dependent upon the hardware employed, including the type
of microprocessor selected, it is not useful to provide detailed
software listings. For completeness, however, FIGS. 4 and 5 contain a
flow diagrams of the manner in which the base and bonus games are
implemented in a processor based system. From these diagrams, those
skilled in the art will be readily able to program the invention
described herein.
[0038] Referring to FIGS. 4 and 5, initially the processor waits until the
player has pulled the handle or pressed a switch to initiate operation of
the game. In addition, it is required that the player has placed a bet,
i.e., that the amount wagered is greater than zero (Steps 100 and 102).
The processor then uses any well known and accepted random number
generator algorithm to choose the symbols for display on the reels of the
base game (Step 104). A tentative value, Total Pay, is computed based
upon a pay table (see, for example, FIG. 3a) for the selected symbol
combination (Step 106). The reels 14, 16 and 18, in the case of the slot
machine 10 of FIG. 1, are spun for a period of time and then stopped so
that the symbols selected appear on the payline (Step 108). Before
awarding credits to the player, in the event a winning combination
appears on the payline, the program, according to the present invention,
first checks to see if 1 WinStreak symbol appears on each reel (Step
110). If so, a bonus game has been earned and the program branches to
Step 112 setting the total pay value to zero and the spin count to zero
in preparation for initiating operation of the bonus game. If WinStreak
symbols do not appear on each reel, either on the payline or above or
below the payline, then the program branches to the circle labeled 6 in
FIG. 5 where the tentative total pay computed in Step 106 is paid or
credited to the player (Step 114) and the game ends (Step 116). As thus
far described, this is the operation of a standard slot machine because
the bonus feature was not invoked. The player must continue playing the
game as described until a WinStreak symbol appears on each reel within
the pay window to initiate operation of the bonus game.
[0039] When that occurs, the program, at Step 112, branches to the bonus
game indicated on FIG. 4 beginning at the circle labeled 2. At Step 118
the bonus game multiplier is set equal to one. The program then checks,
at Step 120, to determine if the three WinStreak symbols are on the
payline. If so, the game multiplier is reset to two (Step 122). In either
case, the program then proceeds to wait for the player to initiate
operation of the bonus game by pressing a button or pulling a lever at
Step 124. This initiates operation of the bonus game display, which in
the illustrated embodiment, is played on the dot matrix display 32 of
FIG. 1. The processor again uses its random number algorithm to choose
the symbols to be displayed for the bonus game (Step 126). A value "Pay"
is set equal to the number of coins associated with the chosen display
combination at Step 128 and the program continues as shown in FIG. 5 in
the circle numbered 4. The Pay value is multiplied by the game multiplier
(Step 130) as a function of the outcome of the decision box 120. A
cumulative value, Total Pay, is computed as being equal to the previous
Total Pays plus the current Pay (Step 132). The program next goes through
the process of providing an animation of spinning reels on the dot matrix
display and as the reels appear to stop, the selected symbols appear
(Step 134). The spin value is then incremented (Step 136) in preparation
for the next cycle of the bonus game. Before commencing the next cycle,
however, it is determined at Step 138 if the player has won or lost. If
he has won, the accumulated winnings are displayed to the player at 140
and the next cycle of the bonus round commences by branching back to FIG.
4 beginning at the circle labeled 3.
[0040] If, however, it is determined at Step 138 that the player has lost,
the program branches to the circle labeled 5. The program then determines
whether the value of the spin counter is equal to one, indicating that
the player lost on his first turn in the bonus round (Step 142). If so,
according to a preferred embodiment of the invention, a consolation award
is given. The program chooses a consolation pay amount (Step 144) using a
random selection algorithm based, for example, on the second chance table
illustrated in FIG. 7. FIG. 7 tabulates the possible pays as a
consolation amount to a player who has achieved the bonus round but lost
on the first spin. The random selection includes amounts of from three to
fifty coins to be paid to the player. FIG. 7 illustrates for each of the
possible pay selections, the number of such selections among a schedule
of 100 memory locations. Thus there are 32 pays of 3 coins, 45 pays of 5,
20 pays of 10, 2 pays of 20, and but one pay of 50 coins. The expected
value for this additional payout is provided in the fourth column of FIG.
7 as 6.11 coins. Since the probability of losing on the first spin is
0.1559 this adds an expected value to the overall game of 0.952536 as
illustrated in FIG. 7 and this is added to the expected win value shown
in FIG. 3 as 26.78072 to obtain the overall payout shown in FIG. 2a of
27.73326.
[0041] After the processor chooses a consolation pay amount, the chosen
pay amount is multiplied by the game multiplier (either one or two) and
the total pay is set equal to the multiplied pay amount (Steps 146, 148).
Finally, the amount of the consolation win is displayed, Step 150, and
then payment is made at Step 114.
[0042] If the bonus round loss occurs after the first spin, the program
goes from Step 142 to Step 114 where the player is credited with the
Total Pay won to that point and the game ends at Step 116.
[0043] In summary, the disclosed embodiment plays a basic game on a reel
type spinning slot machine and a bonus game on a dot matrix display which
may be another type of game or a simulation of a reel type slot machine.
As shown in FIGS. 4 and 5, the basic game and bonus game operate in a
similar manner in a preferred embodiment. With respect to the bonus game,
however, a first Bernoulli trial commences. Symbols are selected for
display, a simulated reel spinning animation, poker display etc. is
provided and then the simulation stops to show the player the selected
symbols. If the combination on the payline or the poker hand is a winner,
the number of coins determined by the pay table is credited to the
player's account. Then a further Bernoulli trial or operation of the game
occurs. This continues as long as each trial produces a winning
combination. In this manner, the player can quickly accumulate a
significant bonus since the hit rate for the bonus game is desirably
greater than 50% and preferably greater than 70%. For a typical game
(i.e. hit rate approximately equal to) designed according to the
invention, it will take between 5 and 6 Bernoulli trails before a losing
combination occurs in the bonus game, providing the player with a large
bonus and a great deal of excitement as he watches his winnings mount.
When, at last, a losing trial occurs, the game is over (unless a loss
occurs on the first trial and the optional consolation or second chance
feature is employed). It should be noted that the Geometric function has
a non zero probability for any number of trials. That is, on occasion 10,
20, 50, 100 or more successive wins in a row are possible.
[0044] There have been various spinning reel slot machine models that
include a feature that will cause the machine to repeatedly spin the
reels until a winning combination appears. Examples of such machines are
WMS Gaming's "Jackpot Stampede" and IGT's "Spin 'til you win". These
models have some added appeal but the shortcoming is that the player's
expectation is crushed once he or she realizes that there is a high
likelihood that the first winning combination to hit will be one of the
"small" awards (i.e. one cherry). It is believed that no one has
heretofore designed a game according to the present invention that allows
a player to spin until he loses, collecting all wins along the way.
[0045] The present invention provides a high hit rate bonus game, so that
the expected number of spins until a loser occurs is greater than 6 for
the described embodiment and the player's winnings adds up quickly. As
the successive Bernoulli trials "fail" (thus extending the game) the
player is winning more and more money. As FIG. 6 shows the probability of
the number of spins is asymptotic to zero. This means that there is a
nonzero probability for each spin count and the bonus game will, on
occasion run through a tremendous number of spins accumulating large
rewards, something that has never been offered before. The joining of a
high hit rate bonus game to a traditional base game is the key to the
excitement of this feature.
[0046] While preferred embodiments of the present invention have been
illustrated and described, it will be understood by those of ordinary
skill in the art that changes and modifications can be made without
departure from the invention in its broader aspects. Various features of
the present invention are set forth in the following claims.
* * * * *