# Slot Probability Function

Please can someone point me in the right direction. I'm working on a slot game. that I'm having trouble figuring how to implement the probability function for. The game has a set of symbols that bets can be placed on. A symbol is selected when the start button is pressed. If there is a bet on the symbol that is selected the player wins a value equal to the [bet]*[bet multiplier]. The bet multipliers work as follows:

• If the selected symbol is marked with x3 it overrides the normal multiplier and the winning value is equal to bet*3 for that symbol.

• If the selected symbol is Apple then the winning value is [bet apple]*5

• If the selected symbol is BAR then the winning value is the bet on BAR multiplied by the multiplier on the selected BAR symbol (x50 or x100).
• The other symbols are grouped into 2 groups of 3 and share a multiplier value that is selected at the time when a symbol on the board is selected. Eg. the orange, lemon and bell form a group. and share a multiplier of 10, 15 and 20. If the selected symbol is lemon and the selected multiplier is 10 the the winning value is equal to [bet lemon]*10.

There is also a luck symbol that have the following 3 outcomes:

1. The player looses.
2. 3 Symbols are selected and winning value is the sum of the bets multiplied by their respective multipliers.
3. A respin is triggered and a new symbol is selected (cannot be a respin but may be one of the other 2 luck outcomes)

The player may also double there winnings by selecting between two options [1-6] or [8-13] a number is generated between 1 and 13 and the winnings are either lost or multiplied by 2.

See the attached pictures for a better understanding of the game.

What I'm having a problem with is figuring out a way to select the outcome of the spin and double feature while maintaining a pay back percentage X% that should hold true over many spins/doubles and that can be adjusted manually.

• Welcome to the Game Dev Stack Exchange. Does the game only select a single symbol per play? How is the outcome of the luck symbol determined - are all 3 outcomes equally likely? By "payback %" do you mean the 'return to player %' (RPT aka 'theoretical payout %')? – Pikalek Jan 20 '19 at 0:02
• @Pikalek Hi, yes and no, when the player hits go a single symbol is selected, however if the selected symbol is luck and the game selects option 2 of the luck outcomes then 3 new symbols will be selected (not including the 2 luck symbols). "How is the outcome of the luck symbol determined" - That's the part i'm stuck on (The probability function for determining which symbol/s are to be selected). "By "payback %" do you mean the 'return to player %' (RPT aka 'theoretical payout %')?" - That is correct :) – MSD Jan 20 '19 at 0:41