U.S. patent application number 08/835840 was filed with the patent office on 2001-07-26 for gaming machine with bonus mode.
Invention is credited to DEMAR, LAWRENCE E., FROHM, ERICA.
Application Number | 20010009865 08/835840 |
Document ID | / |
Family ID | 25270606 |
Filed Date | 2001-07-26 |
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 micro-processor in
which the first mode of operation, a basic gambling game, is
implemented such as video poker or reel-type 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 micro-processor 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
|
Family ID: |
25270606 |
Appl. No.: |
08/835840 |
Filed: |
April 23, 1997 |
Current U.S.
Class: |
463/20 |
Current CPC
Class: |
G07F 17/3267 20130101;
G07F 17/3244 20130101; G07F 17/32 20130101; A63F 3/00072 20130101;
A63F 2007/0064 20130101 |
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 micro-processor 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 three-symbol 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 micro-processor based machines have
been developed. The game is played in the micro-processor 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 reel-type
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 reel-type 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 play-until-you-lose-mode 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 hit-rate 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 reel-type 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 four-of-a-kind 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 reel-type 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 micro-processor 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 video-type
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 B-A.
[0029] A principal feature of the invention is the high hit rate of
the bonus game coupled with the spin-til-you-lose 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
2-coin, 3-coin, 5-coin 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
B-A from the preceding discussion times the EV of the bonus game or
((B-A)*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 non-winning spin). For more information on Bernoulli
trials see, for example, Hogg and Tanis "Probability and
Statistical Inference" 4ed. pp. 150-171, 1993 Prentice-Hall
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 spin-til-you-lose 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
micro-processor 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 non-zero 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.
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