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RTP, RNG, Volatility: Slots machine algorithms explained

Slot machines, also known by various names like “one-armed bandits,” “fruit machines,” or “pokies,” have evolved from their early mechanical forms into captivating digital entertainers. Their origins can be traced back to the late 19th century, and they generate about 70% of the average U.S. casino’s income.

Many believe that slot machines, including online slot games, operate on randomness, with payouts controlled to ensure a specific percentage of played money is returned, typically around 90%. This implies that the outcome of the game relies solely on luck.

However, beyond the flashing lights and catchy sound effects lies a complex world of algorithms that govern their operation to ensure fairness. Contrary to popular belief, the concept of randomness in slot machines is not as simple as it may seem. Slot machines must strike a delicate balance between unpredictability and controlled payout distribution.

Understanding the inner workings of these algorithms, including RTP (Return to Player), RNG (Random Number Generator), and volatility, might be the key to mastering the reels.

Understanding RTPs

Online casinos enable players to choose from tens of thousands of options for slot games. To help them choose, these platforms usually include something called RTP within the game’s description.

RTP is a crucial metric that represents the percentage of wagered money a slot machine is programmed to return to players over time. Essentially, it reveals the house edge in reverse. The higher the RTP, the lower the house advantage.

This evidence suggests that a higher RTP suggests a higher likelihood of regular payouts. For instance, when you play a game with 98% RTP, you might get 98 coins for every 100 coins you spend over time. On the contrary, you will only get 87 coins back from every 100 coins you spend on a slot with only 87% RTP.

The affair between RNG and fairness

At the core of many video games and every modern slot machine is the RNG. This algorithm ensures the randomness and fairness of outcomes. It can generate thousands of numbers every second, and each number corresponds to a specific result on the slot’s reels.

This algorithm freezes a set of numbers and matches them to the game’s symbols when the spin button is clicked. The sequence determines your results, but the system ensures that every spin is entirely independent of the previous one.

RNG and RTP go hand in hand. Game creators usually set a desired RTP range before programming the RNG algorithm. The RNG software is then fine-tuned to ensure that the theoretical RTP aligns with the intended value over a substantial number of game rounds, typically exceeding 1,000.

Embracing volatility

Behind the scenes, software developers meticulously craft the game’s design and probabilities to deliver the desired player experience. These colourful machines may be designed to captivate and entertain, but they also run with intricate algorithms rooted in probability theory and mathematics. The game’s volatility is one.

Also known as variance, volatility measures the level of risk involved in a game. Low volatility slots deliver frequent albeit smaller wins. Meanwhile, high volatility slots offer less frequent but potentially larger payouts.

When choosing the game, it is important to consider both volatility and RTP. Volatility refers to the risk and frequency of payouts, while RTP indicates the percentage of bets returned as winnings over time.

Ultimately, the decision boils down to a single, fundamental choice: opt for high volatility with low RTP or go for low volatility with high RTP. It depends on the type of the game and your own preference. High volatility coupled with low RTP will be more fitting for risk-takers. On the other hand, the combination of low volatility and high RTP is more likely to fit players looking for consistent, prolonged gameplay and a lower risk of significant losses.


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