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[[File:Slot Machine.gif|left]]
[[File:Slot Machine.gif|left]]
[[File:Slot Machine Rewards.png|right|340px]]
[[File:Slot Machine Rewards.png|right|340px]]
'''Slot Machines''' are a type of mini-game in ''[[Stardew Valley]]''. They are found in the [[Casino]].
'''Slot Machines''' are a mini-game found in the [[Casino]].


The player can bet either 10 or 100 Qi coins when using a slot machine. If the results match one of the winning lines, the player receives a multiple of their bet. If there is no match the player loses their bet. [[Luck]] has an effect on gambling odds when using the slot machines.
The player can bet either 10 or 100 Qi coins when using a slot machine. If the results match one of the winning lines, the player receives a multiple of their bet. If there is no match the player loses their bet.  


Daily [[Luck]] and Luck buffs (from [[cooking|food]] items, [[Ginger Ale]], [[Lucky Ring]]s, etc.) can increase the chance of winning and the expected return when gambling. Otherwise, rolls are randomly determined.


==Winning lines==
There are 10 possible winning lines, each one giving different multipliers.
{| class="wikitable sortable"
|-
!Line
!Chance<ref name="slots"/>
!Multiplier
|-
|[[File:Cherry.png|32px]]
|20%
|2
|-
|[[File:Cherry.png|32px]][[File:Cherry.png|32px]]
|10%
|3
|-
|[[File:Parsnip.png|32px]][[File:Parsnip.png|32px]][[File:Parsnip.png|32px]]
|8%
|5
|-
|[[File:Large Milk.png|32px]][[File:Large Milk.png|32px]][[File:Large Milk.png|32px]]
|1%
|30
|-
|[[File:Rainbow Trout.png|32px]][[File:Rainbow Trout.png|32px]][[File:Rainbow Trout.png|32px]]
|0.3%
|80
|-
|[[File:Nautilus Shell.png|32px]][[File:Nautilus Shell.png|32px]][[File:Nautilus Shell.png|32px]]
|0.2%
|120
|-
|[[File:Melon.png|32px]][[File:Melon.png|32px]][[File:Melon.png|32px]]
|0.25%
|200
|-
|[[File:Cherry.png|32px]][[File:Cherry.png|32px]][[File:Cherry.png|32px]]
|0.09%
|500
|-
|[[File:Diamond.png|32px]][[File:Diamond.png|32px]][[File:Diamond.png|32px]]
|0.06%
|1000
|-
|[[File:Stardrop.png|32px]][[File:Stardrop.png|32px]][[File:Stardrop.png|32px]]
|0.1%
|2500
|}


This is adjusted multiplicatively by daily Luck, increasing by 20% at best or decreasing by 20% at worst with the [[Special Charm]] adding 5%. Food buffs add 8% for every point of Luck (''e.g.,'' if daily Luck is max and luck from food is 3 then the chance to get 1 cherry is 20% * (1 + 0.2 + 0.24) = 28.8%).


The slot machines have certain patterns that can be exploited. By betting 100 when expecting a win and 10 when expecting a loss, you can quickly obtain enough Qi coins to buy an item from the shop. The order of the patterns may vary depending on your luck.
==Expected Value Calculation==


On a day with a little [[Luck]] there are three patterns that occur in some order:  
To calculate the expected net gain or loss from playing the slot machine, we use the formula:
*16 losses then W-L-W-L-W-L-W
*14 losses then W-L-W-L-W-L-W-L-W
*14 losses then W-L-W-L-W-L-W


From playing 8 repetitions of the above patterns (14 or 16 losses followed by 4 or 5 W/L) the 5 W/L happened once. The highest observed match at the time was 3x shells.
'''Net Expected Gain/Loss = (B × Σ(P<sub>i</sub> × M<sub>i</sub>)) - B'''


On a day where the spirits are displeased this pattern was observed:  
Where:
*12 losses then W-L-W-L-W-L
* ''B'' = Bet amount (in units)
*16 losses then W-L-W-L-W-L
* ''P<sub>i</sub>'' = Probability of the i-th outcome
*18 losses then W-L-W-L-W-L
* ''M<sub>i</sub>'' = Multiplier for the i-th outcome
*18 losses then W-L-W-L-W-L
* ''Σ'' = Sum over all possible outcomes (i=1 to n)
*16 losses then W-L-W-L-W-L
*18 losses then W-L-W-L-W-L
*18 losses then W-L-W-L-W-L
*18 losses then W-L-W-L-W-L
*18 losses then W-L-W-L-W-L


The highest observed match at the time was 3x parsnips.
After accounting for the following:


'''Net Expected Gain/Loss = B × ((0.2 × 2) + (0.1 × 3) + (0.08 × 5) + (0.01 × 30) + (0.003 × 80) + (0.002 × 120) + (0.0025 × 200) + (0.0009 × 500) + (0.0006 × 1000) + (0.001 × 2500)) - B'''


Starting a new round of slot play will require {{Price|300|Qi}} (18 losses x 10 = 180 + 100 high bet).  
Which simplifies to:
 
'''Net Expected Gain/Loss = B × 5.93 - B = B × (5.93 - 1)'''
 
Then reducing to:
 
'''Net Expected Gain/Loss = B × 4.93'''
 
To simplify, if you spend {{Price|100|Qi}} on a spin you can expect a net gain of {{Price|493|Qi}} per spin!
 
==References==
<references>
<ref name="slots">See <samp>Slots::setSlotResults</samp> in the game code.</ref>
</references>
 
==History==
{{History|1.4|Recalculated the way random number generation is done, removing repeating pattern exploits.  All [[Casino]] games now slightly favor the player rather than the house.}}


[[Category:Mini-games]]
[[Category:Mini-games]]


[[de:Spielautomat]]
[[es:Tragaperras]]
[[es:Tragaperras]]
[[fr:Machine à sous]]
[[it:Slot machine]]
[[ja:スロットマシン]]
[[ko:슬롯 머신]]
[[hu:Pénzbedobós automata]]
[[pt:Caça-níqueis]]
[[ru:Слот-машина]]
[[tr:Slot Makinesi]]
[[zh:印花老虎机]]

Latest revision as of 14:14, 18 March 2026

Slot Machines are a mini-game found in the Casino.

The player can bet either 10 or 100 Qi coins when using a slot machine. If the results match one of the winning lines, the player receives a multiple of their bet. If there is no match the player loses their bet.

Daily Luck and Luck buffs (from food items, Ginger Ale, Lucky Rings, etc.) can increase the chance of winning and the expected return when gambling. Otherwise, rolls are randomly determined.

Winning lines

There are 10 possible winning lines, each one giving different multipliers.

Line Chance[1] Multiplier
20% 2
10% 3
8% 5
1% 30
0.3% 80
0.2% 120
0.25% 200
0.09% 500
0.06% 1000
0.1% 2500

This is adjusted multiplicatively by daily Luck, increasing by 20% at best or decreasing by 20% at worst with the Special Charm adding 5%. Food buffs add 8% for every point of Luck (e.g., if daily Luck is max and luck from food is 3 then the chance to get 1 cherry is 20% * (1 + 0.2 + 0.24) = 28.8%).

Expected Value Calculation

To calculate the expected net gain or loss from playing the slot machine, we use the formula:

Net Expected Gain/Loss = (B × Σ(Pi × Mi)) - B

Where:

  • B = Bet amount (in units)
  • Pi = Probability of the i-th outcome
  • Mi = Multiplier for the i-th outcome
  • Σ = Sum over all possible outcomes (i=1 to n)

After accounting for the following:

Net Expected Gain/Loss = B × ((0.2 × 2) + (0.1 × 3) + (0.08 × 5) + (0.01 × 30) + (0.003 × 80) + (0.002 × 120) + (0.0025 × 200) + (0.0009 × 500) + (0.0006 × 1000) + (0.001 × 2500)) - B

Which simplifies to:

Net Expected Gain/Loss = B × 5.93 - B = B × (5.93 - 1)

Then reducing to:

Net Expected Gain/Loss = B × 4.93

To simplify, if you spend data-sort-value="100">100 on a spin you can expect a net gain of data-sort-value="493">493 per spin!

References

  1. ↑ See Slots::setSlotResults in the game code.

History

  • 1.4: Recalculated the way random number generation is done, removing repeating pattern exploits. All Casino games now slightly favor the player rather than the house.
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