What makes the New Released Keno game so Different?

Guess what? Payouts are related to the odds…

BetSwirl.eth
4 min readJun 16

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What’s the original Keno?

Keno is a lottery-style game where players select up to a certain amount of choices from a select pool of options. Afterwards, a certain amount of selections are randomly drawn and the player can win depending on how many of their chosen choices match the drawn selections.

The most common Keno variation has a pool of 80 numbers and allows the players to choose up to 10 while it rolls for 20 different results.

How is BetSwirl’s Keno different?

BetSwirl’s Keno variation is structured in a way that the game format is aligned with the goals of the project. For that reason BetSwirl launched a Keno variation with a pool of total 15 numbers with players being able to choose up to 4 (this might change depending on the chosen token).

The reason we started with a lower than traditional Keno’s pool number is that we didn’t want to use arbitrary pay-out multipliers so we can maintain a sustainable bankroll management for the protocol because in that way the casino’s house edge would deviate depending on the choices of the player.

All the multipliers are equally fair and are actually reflecting the real chances of that outcome occurring like every other game on BetSwirl so far.

BetSwirl’s Keno payout table

How does BetSwirl use maths to build a provably fair Keno?

Unlike most of the available Kenos in the market in BetSwirl we reward the player with a fair multiplier on each of his bets minus the house edge %.

This means that the multiplier always reflects the true odds and is calculated through the formula of “Hypergeometric Distribution”, which is a probability distribution used to calculate the probability of a particular number of successes from a given population size.

The Hypgeom.dist function

You can check out this quite interesting formula in Excel/Google Sheets named Hypgeom.dist. This is the exact formula that calculates the chance of a certain outcome from a given population size.

For example if you wanted to determine the chances of randomly selecting 10 items out of a population of 100 and having 7 of them be successes, the hypegeom.dist function can help a lot. It takes four parameters : population size, number of successes in the population, sample size and number of successes in the sample.

The function will return the probability that randomly selecting items out of a population will result in a certain number of successes.

Why you never lose 100% of your bet?

Something that a lot of people who first get in touch with Keno or Keno’s payout tables (like the one you saw above) are surprised with is that in Keno players are always getting a prize regardless of the result. This is not necessarily true for every Keno variation out there but it is for BetSwirl’s.

The reason a lot of people think this is “weird” is because they don’t understand why any casino would offer the players the chance to bet on a game that pays them back always regardless of the result as this would “surely” make the casino end up broke. “Surely?” Surely you would not think so if you have read our articles about what EV is 😉 No casino would ever offer a game that would not be profitable for the house in the long term and Keno is no exception.

In a few words, high frequency of winning does not guarantee a profitable bet. As we previously explained each possible outcome has specific chances of occurring if for example a player choses 3 numbers he can hit either 0/3, ⅓, ⅔ or 3/3 and this will happen 100% of the time. Of course each outcome has some different non-zero chances of occurring and the sum of the probability of each outcome equals to 1 (100%) so in any of these cases the player is going to get back his bet multiplied by the appropriate-fair multiplier minus the % House-Edge.

What is BetSwirl’s Keno house edge?

The same as the other games, it depends on the wagered token:

  • Gas tokens (MATIC, BNB, AVAX): 3%
  • BETS: 2.5%
  • Partner tokens: 3.5%

How to play it?

Playing Keno is very easy…

Just select up to X numbers from the total Y pool of numbers. Then ChainLink will randomly draw Z numbers and depending how many you got right from 0 to X you will get rewarded by the appropriate multiplier.

Good Luck !

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