Carnival Slots is a documented design for a casual slot machine game. The game is setup with three reels and seven symbols appearing in unique probabilities on each reel. The game includes a progressive payout system and bonus game playable on a particular winning combination. All probabilities and payouts have been calculated and balanced to keep the return rate within a desired range.

Carnival Slot System Design Doc

Carnival Slot System Calculations Spreadsheet

Theme: Carnival/Carnival Games

Reel Configuration

Symbols:

• “Carnival” sign (CSN)
• Golden Ticket (TIX)
• Balloons (BAL)
• Popcorn (POP)
• Ferris Wheel (FW)
• Candy Apple (CAP)
• Clown (CLN)

Reel 1

Symbols	Frequency
CSN	3
TIX	3
BAL	3
POP	5
FW	4
CAP	4
CLN	3
Total	25

Reel 2

Symbols	Frequency
CSN	2
TIX	2
BAL	3
POP	5
FW	6
CAP	4
CLN	3
Total	25

 

Reel 3

Symbols	Frequency
CSN	1
TIX	2
BAL	3
POP	6
FW	5
CAP	5
CLN	3
Total	25

 

Payout Matrix

Winning Combination	Payout
CSN, CSN, CSN	250
TIX, TIX, TIX	150
BAL, BAL, BAL	100
CLN, CLN	75
CAP, CAP, CAP	50
FW, FW, FW	15
POP, POP, POP	5

 

Return Calculations

Symbols	Payout	Return	ChanceToHit
CSN, CSN, CSN	250	0.096	0.000384
TIX, TIX, TIX	150	0.1152	0.000768
BAL, BAL, BAL*	100	0.1728	0.001728
CLN, CLN, CLN	75	0.1296	0.001728
CAP, CAP, CAP	50	0.256	0.00512
FW, FW, FW	15	0.1152	0.00768
POP, POP, POP**	5	0.048	0.0096
Progressive	0.05	0.05	1

(Full spreadsheet available at https://docs.google.com/spreadsheets/d/1mLdcY83yo_y9pWsgPQ6_0xJnhxncSu5QYaK5ODPAYkU/edit?usp=sharing)

Payout Rate = .9328 + .05 (Progressive return) = .9828 = 98.28%

*Bonus Game – average payout over time for the bonus game. See Bonus Game section for details.

**Payout Reduced to accommodate return of progressive system

Progressive System

This progressive system takes .05 cents from each dollar spin to add to a progressive jackpot paid out on hitting three Carnival signs. Initially, in designs prior to adding the progressive system, the hit of three Popcorns paid out $10. This provided the system with a 98.08% return. With the addition of the progressive system, the Popcorn payout was reduced to $5 to accommodate the additional return. This reduction resulted in an overall return of 93.28%. Adding the 5% progressive return back into the system results in the final return of 98.28%.

 

Bonus Game

In this bonus game, the player will select balloons from a set to pop. The set of balloons will be 4×4 (16 balloons in total) and the player will select 4 to pop. Balloons will contain either $0 or $50 in an equal distribution of 8 balloons each arranged randomly on the board. Players will earn the cumulative amount from the 4 balloons they have selected.

 

The player will have four darts representing the four selections they may make. Each balloon will contain either $50 or $0 (eight balloons of each).

 

Clicking on a balloon will pop that balloon revealing its contents.

 

After all four darts have been used, the game will total the winnings from the selected balloons and present the total winnings from the bonus game to the player.
The probability of selecting some combination that rewards the potential payouts is as follows:

Amount won	Probability
$0	105/2730
$50	672/2730
$100	1176/2730
$150	672/2730
$200	105/2730

Given these probabilities, if 2730 games are played, the total payout amounts will be the following:

105 games x $0 = $0

672 games x $50 = $33,600

1176 games x $100 = $117,600

672 games x $150 = $100,800

105 games x $200 = $21,000

Total Payouts = $273,000

$273,000 / 2730 plays = $100 per play