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How slot games work

We discuss the casino's advantage over the player and if there are any working strategy. Learn about the chances of winning and the history of slots.

The Basics of Slot Machine Operation: PRNG

Almost all online slot machines operate based on pseudorandom number generator software, abbreviated as PRNG. As soon as you hit the spin button, this software determines your winnings even before the animations visible on the screen run through. 

The PRNG software is designed to provide a guaranteed percentage of profit for the casino in the long run. However, the player's experience is equally important for the casino, so the software operates to provide exciting amounts and frequency of winnings. This also results in days when the slot machine generates a loss for the casino.

We can understand the software's task as drawing for you from a predefined prize structure - similar to what you see on the back of scratch-off tickets.

Winning Odds, Return

In the long run, the return value of these games typically ranges between 85% and 96%, meaning the casino operates with a profit between 4% and 15% on the machines. This places slot machines in the middle of the field in terms of gambling games, as they perform much better than lotteries or scratch-off tickets, but worse than blackjack or video poker. The game's return value can be viewed in the help menu. 

Regarding winning odds, we must discuss the concept of volatility. Volatility is a property of the machine that determines how frequently it pays out winnings. The lower the volatility, the more frequently it pays out. However, the more frequently it pays out, the smaller the value of the winnings will be on average. 

For many machines, the player can even adjust the volatility. On very volatile machines, we can win up to 50,000 times our bet with a single spin, while on low volatility machines, a few hundred times. 

It's worth mentioning a popular type of slot machines, the Progressive Jackpots. For these games, the jackpot is not a fixed multiplier of your bet, but a growing sum, typically a few million dollars. This is created by setting aside a portion of the bet you place into a prize pool. This essentially gives the game a very high volatility.

Types of Slot Machines, Evolution

The oldest and simplest version is when you have three reels and the same pattern must appear on the middle line of all three reels for a win. Classic patterns are fruits, card symbols, the number seven, or the BAR inscription. 

The next step in the evolution of gaming machines is that the player can win not only with one line but with multiple ones, and even in all sorts of zigzag directions. Sometimes the arrangement of symbols doesn't even matter, only the quantity on the screen.  Moreover, the three reels also increased to five or more to represent additional winning possibilities. 

The greatest variety in slot machines is due to the theme around which the graphics and sounds are built. You can find a slot machine for almost any movie, action hero, fantasy world, cultural, or historical event. 

The next big leap was brought by the "game within a game" experiences. Typically, by spinning or collecting special symbols, we can participate in bonus games, which usually come with an intense audiovisual experience and significant winnings. The simplest type of "game within a game" is when we receive a certain number of free spins and possibly an extra multiplier for winnings.

As for the most modern slot games, they increasingly resemble RPG games: they take place in a 3D world, have scenes with a storyline, and contain skill parts that can very slightly influence the return value.

Slot Selection, Strategy

You may be wondering which slot machine would be worth trying? We have two pieces of advice for this:

  1. Choose one that has a high return value. As a general rule, from an amount sufficient for about a hundred spins, you can play for approximately one hour before you lose it. This, of course, depends on your luck, the machine's volatility, and return value.
  2. Our second advice is to choose a game that you find enjoyable. Unfortunately, with modern, online slot machines, there are no tactics or betting strategies that could significantly influence the casino's advantage in the long run. Regardless, there are slot machines where the player can choose from several strategies, and the machine will start playing automatically according to that choice.
  3. There are also skill-based slot games, though these are very uncommon and quite rare. These games often resemble arcade games. If you play well, you can increase the Return to Player (RTP) by a few percentage points, but it won't make the game profitable.
  4. From a theoretical point of view, it's possible to encounter a situation on a progressive jackpot slot machine where the Return to Player (RTP) is above 100%. This can only occur if the current jackpot level is high enough. This situation is similar to when a lottery jackpot is so high that it would be worth buying all the combinations (assuming no one else would win the jackpot).