Slot Mechanics

The online gambling industry is growing at its fastest ever rate and by 2023 this is estimated by Statista to be worth $92.5 billion by 2023 and it is easy to understand why that is. One of the reasons for this growth can be attributed to one particular niche within the online gambling industry which continues to generate a considerable amount of interest on a regular basis which is that of jackpot slots.

Over the last few years, these have exploded in popularity and for good reason, with a considerable amount of jackpot slots now available at many numerous online casinos. This has led to certain software providers specialising in the creation and development of jackpot slots, with some such as NetEnt establishing themselves as a serious force to be reckoned with.

As a result of this, some of the most popular jackpot slots in the industry are provided and developed by NetEnt and it is no coincidence that these offer the biggest jackpots that you can find.

Perhaps the biggest selling point of NetEnt jackpot slots is the sheer amount of work that goes into them. Over the last couple of decades, the software provider has built up a supreme reputation in the online gambling industry and as a result are highly respected by, not only their competition but also numerous operators in the marketplace.

Their technical knowledge of the industry makes sure that they are able to continue to lead the way in the development of slots and jackpot slots in particular, especially in recent years.

This is seen as an important and considerable factor when it comes to creating new jackpot slots because there are so many other different software providers in what is one of the most competitive parts of this industry. With a substantial amount of jckpot slots released on a yearly basis, it is important that software providers are able to do enough in order to help differentiate from their competition.

It is one of the reasons, why this fundamentally comes down to technology and being able to develop new ways of programming slots in a way that they can help attract more players. This could be that a new jackpot slot all of a sudden becomes faster or slicker than any of its predecessors, with rapidity of gameplay often playing a big factor in a jackpot slot fan’s experience.

NetEnt have always been at the cutting edge of technological development, especially when it comes to new products and following their recent acquisition by Evolution Gaming, early signs indicate that they are now well positioned to further improve their jackpot slot offering.

Throughout this guide, we have gone into comprehensive detail about the mechanics of a jackpot slot and what each one is, including about what they do and the possible implications that they can have on a player’s experience. This will also help you to understand a lot more about how they are created and designed as well.

Understanding the mechanics of a jackpot slot

Looking at a slot when visiting an online casino (or even playing one) is like looking at a car through a showroom window. You can see a highly polished, aesthetically attractive product, but you perhaps do not realise the amount of work that has gone into it to get it looking the way that it does.

Like a car with its various different wires and pipes (especially underneath the hood), this is very similar with a jackpot slot. In fact behind the amazing and vibrant imagery is the equivalent of the wiring that you would find in a car, in the form of hundreds, if not thousands of lines of highly complex code and mathematical algorithms. These all have a specific job in relation to how the slot functions for the purpose of the player.

All of these mechanics that are in place for a slot enable the slot to function how it should and because of this, it is one of the reasons why so much investment is required from the start to make sure that the chances of any kind of errors are minimsed as much as they possible can be.

What is also worth taking into account is the fact that the majority of the technical elements of the jackpot slots are often influenced by the purpose of the jackpot slot itself, in terms of what the player has to do and the particular theme that it is based on, in addition to things like payouts.

Arguably the most clever part of a jackpot slot is the technology that recongises if a winning combination has been made and then how the actual slot should respond to this, especially if there are many different possible paylines. Then perhaps what is even more impressive is how the jackpot slot calculates the amount that the player has won, especially if this happens at the same time for many different players, which with jackpot slots is entirely possible.

In addition to this, there are different types of jackpot slots as well and as a result of this, each one differs in terms of how it is programmed, especially if it is either for a local jackpot or a network jackpot. NetEnt in particular have a great number of both of these types of jackpot slots and all of these differ in terms of what they can and cannot do.

In addition to this, there is also some slight contrast in terms of how they are designed and exactly what the player needs to do and the length of time that it might take them, in terms of the amount of spins that they might need to make or how often bonus rounds are unlocked and what they look like or the differences between the various wilds that might be on offer and what they do.

Technical elements of jackpot slots

When thinking about jackpot slots, there are many different components to bear in mind, especially from a development perspective. Let’s take a look at some of the main ones and exactly what their purpose is.

Random Number Generator

This is a very fundamental part of a jackpot slot and arguably is the most important. Also known as the RNG, a lot of expertise goes into the developments of these. Below we have taken a closer look at how jackpot slots make sure these can function in a way that exceeds technological expectations.

What is the Random Number Generator and why is it important?

Essentially the core principal for online slot machines and also by extension, jackpot slot machines, is to make sure of a completely random outcome for their players. This means that, because they are machines, it means that the randomness of the possible outcome has to be programmed into the logic that the software can then apply.

Although the creation of randomness using mathematical software is in theory impossible, because that would therefore mean that if you can use an equation for this then it would mean that you can determine an outcome. However, the beauty of this and the way round it, is that the particular algorithms that are needed in order to do this can be put together with these two attributes.

  • No pattern is to be repeated
  • There is a standard deviation which means that over a particularly long time period the distribution of the possible outcomes is ultimately even

Should there be a pattern being repeated then this means that an outcome can be pre-defined and as follows mean that there is no randomness assigned to the outcome. However, if there is not a repeatable pattern that occurs inside the mechanics of the slot, then this naturally means that the outcome or the results can deemed to be random.

If the results are not deemed to be evenly distributed over the long term and the results are skewed because of this, then this would mean that there is not any randomness in the slot.

As such, it appears that randomness can be achieved by fulfilling the attributes of an unrepeatable pattern as well as an even distribution over the course of a significantly lengthy amount of time playing the slot.

Outcomes for jackpot slots in relation to the random number generator

In a jackpot slot, you will find that random numbers are continuously, albeit regularly being generated, regardless if there is no game being played at all. As is the highly sophisticated nature and capability of the software tht is used to create an develop the slot, it means that the outcomes of every algorithm are consistently being worked out at a rate of thousands per second, which even to the most advanced mind, is seemingly incomprehensible. The sheer volume of this rate is though made possible by the slots being connected to the main server, which helps to enable such an impressive rate of calculations. As such, the results of a win or a loss are then worked out by the slot itself, based on the factors and variables that determine which one of these is relevant.

When you are aware of this, it means that you are then able to come to the conclusion that it is not remotely possible to make any kind of prediction about the outcome or result of playing a slot, especially because thousands of calculations take place every single second in order to generate a consequence.

The only exception to this is if you know the logic of the algorithm which would then provide the key to being able to work out a result and even then, you would have to calculate this almost instantly before the slot itself. It is essentially impossible.

Different types of random number generators in slots and their mechanics

While you might have thought that there was just one type of random number generator that the online gambling industry uses, you would be mistaken. Each of the different ones are more suited to specific slots based on what their purpose or objective is, so let’s take a look a the different types!

PNG (Pseudorandom Number Generator)

This type of random number generator is able to distinguish itself in a number of different ways. The first one being that the PNG uses mathematical algorithms in a precise and specific order and crucially, this is decided by the actual software provider.

As a result, this means that the software provider will create a software algorithm and the easiest way to think about this, is that it is essentially in the form of a roulette wheel while working out calculations for the next result on a continuous basis. This means that when a player begins or resumes playing an online slot, it means that the combination has already been predetermined.

Firstly, it means that thousands of digits are used and in this particular instance it is the ‘number’ π (this is basically a sequence which has in excess of five trillion digits). Following this, the rest of the value is then set by a number of mathematical processes, which includes addition, subtraction, multiplication and division in all of their forms. This type of random number generator is subsequently used by the majority of online slots.

HRNG (Hardware Random Number Generator)

What you will typically find is that a HRNG will produce random numbers by making use of compound values. This is a random number generator that you will typically find in more land based gambling establishments, though jackpot slots are available both online and in physical casinos, especially if they are on a network.

Essentially, a mechanism records radioactive isotope at a rate of a number of different electrons being produced each second. A number of starting points are subsequently used in order to prouce these numbers with all of them being completely random and as a result are then generated by different physical objects.

Why it is important to understand what the random number generator does

First of all, there are very few players of online slots who have even heard of a random number generator, let alone what it does, so this means that you are already ahead of the game if you are reading this.

The reason why it is key to understand about what they do though, is because the RNG is virtually the most important element for determining a player’s odds of winning at every single second of gameplay. This means that when you understand the key roles of the random number generator then it can help you to minimise your losses.

In addition to this, it can also help you to make a decision about the size of your bankroll and what degree of risk that you apply based on what you already know. Being aware of what a random number generator does can also help to formulate your own strategy for playing your jackpot slot.

Despite the fact that this makes sure that the slot reveals numbers on a completely and consistently random basis, there are other things that you can take into account. For example, if you have only been playing for 10 minutes but you are getting small but regular payouts, then you can deduce that although the random number generator is at work (which can tell you that these payouts might become less frequent), that it is a jackpot slot that has a low volatility rate.

As a result of this, it can then help you to formulate a strategy. Perhaps this could include you choosing another slot to play and revisiting that particular one after a certain period of time.

What are starting numbers and seeding?

Every single algorithm needs to have what is called a ‘starting number’ in order to begin the calculation of randomness. As a result of this, the starting number is also referred to as the ‘seed’. Based on this logic, it means that if two slots use exactly the same starting number and also have the same algorithm associated with them, then it follows that the results the sots generates are identical.

Delving deeper, you would also see that every number (or calculation) that the slot machines go through each second to produce a result, would also be exactly the same, based on the fact that they used the same starting number. Despite this though, unless an individual was able to access the data and analyse this then it would appear on the face of it that both slots were individually unique and as such could be deemed to be random.

When it comes to the starting number, programmers of jackpot slots will either choose them based on what is called a ‘fixed logic’ such as the day’s date or it can be selected based on a particular random event which might be the average rate at which an aeroplane accelerates at while it is taking off.

Connecting this advanced computer software to such a randomly external event can be done, however, it is substantially more difficult to incorporate this into a system and as a result of this, the majority of systems make use of a fixed logic event as a way of deciding on the starting number.

Volatility levels

Every online jackpot slot has a specific volatility level and these play a very important role in how they function on a regular basis and can also provide a clue as to whether a slot might be working properly based on the results that are being yielded. Let’s take a more in-depth look at this.

What is slot volatility and how does it apply?

One of the most important things that seasoned online slot players look for before playing a slot and which can often have a considerable influence in their decision making process, is what volatitlity level that a slot has.

Slot volatility takes into account the risk versus reward concept that a player might factor in and because of this, it can sway a player either way. There are three different volatility levels and every online slot has one of these applied.

Low Volatility

When a slot has a low volatility level, it means that players will receive payouts frequently, however they will win lower amounts. This can be especially good for jackpot slot players, who are focused on winning the grand prize, because it essentially gives them a chance of making sure that they have a regular bankroll to try and enable this.

Low volatility slots are often played by ‘casual gamblers’ who just really want to have fun and will have a low bankroll in mind, that once it has been lost, they will then stop. These are also ideal for beginner players who are new gambling, because less risk is required with these in order to get started, though there is also often the possibility to play in demo mode first for free to become more comfortable and get used to it.

High Volatility

It is worth mentioning firstly that you should only play slots that have a high volatililty level if you have a generous degree of patience, though also a substantial bankroll and a greater appetite for risk. This is because you will find that payouts are a lot less frequent statistically, however payouts are much larger. It therefore means that you might have to wager more than you would for lower volatility slots, however, if you are lucky and because of the fact that a random number generator is in play, you might not need to wager much. As we explored above, a random number generator has no memory which means that it would not know how long you have been playing a particular slot for.

Typically, high volatility slots appeal more to ‘die hard’ gamblers who are used to waiting long periods of time for a possible payout and are prepared to essentially lose a certain amount of their bankroll because they are aware of how the slots work.

Medium Volatility

There are much more of these available than there was. However, defining exactly what a ‘medium volatility’ slot has in terms of being able to differentiate them between a low and a high volatility slot can be challenging. Essentially a slot with a medium volatility rate is a balance between low and high. However, putting an exact number on this is hard because of the varying possible degrees of ‘medium volatility’.

One recommended tip that you can apply to determining whether a slot has a medium level of volatility is to see after how many spins your second payout comes. On average a slot that has been assigned a medium level of volatility will typically pay out after between 20 and 30 spins.

They are known to be a lot more frustrating than the slots of the other two volatility levels, because players do not have a clue what to expect fom them. While they may already know that payout amounts will not be very low, it is hard for them to be able predict how much they might receive, especially if the slot has a particularly big reputation in the marketplace and as a result, attracts a considerable amount of players on a regular basis.

Understanding the relationship between the random number generator and volatility levels for jackpot slots

There is an obvious question that relates to this. How does the random number generator know what volatility level a jackpot slot has and how is this programmed from the beginning?

Looking at the specific mechanics of a slot and how they are programmed, it could well naturally follow that the random number generator knows or at least should know what the volatility level of a specific slot is.

In simple terms, you would have to go right back to the starting number and relevant sequence in order to essentially give the slot the correct information that it then needs in order to function at its designated volatility level.

RTP in jackpot slots

This plays a hugely fundamental part of a player’s decision when it comes to making a choice about which jackpot slot to choose. It is one of the most important mechanical attributes that you will find in a slot and as such you will typically read a great deal about this. Let’s explore more about RTP in detail and what it is.

What is RTP?

This stands for ‘Return to Player’ and refers to the rate at which a player can expect to get paid out when playing a particular slot. This is presented as a percentage on (or below/above) the slot itself. The way in which it works and functions is that it describes the amount that you can expect the slot to pay back to you over what is usually a particularly high number of spins and this is presented as a percentage. An easy way of looking at this in a way that makes it simple to understand is that, if a slot has a return to player rate of 97 percent, then you can expect to get £97 back out of £100 that is wagered.

However, what is key to understand is that this number is worked out based on millions of spins, which means that a truer representation is that while you are playing, literally anything can happen and this is why those who understand exactly what RTP relates to find online slots exciting. It is worth noting that NetEnt jackpot slots boast some of the most favourable and attractive RTP percentage rates in the industry.

How does the RNG know what the RTP of a slot is?

Because the return to player of a slot is calculated based on millions of spins, not just from one player but thousands of others who may be playing the slot at online casinos around the world, it is essentially theoretical. As such, it means that winnings will not be produced every time a player plays the game but rather the consequence of this is an average.

Just like the random number generator, the results are entirely random and because of this, the only effect that the RNG has on the RTP is the way in which it has been programmed. Because of this, there would be no way of knowing what the RTP of a slot would be while developers are in the infancy of engineering the intricacies of a starting number for the RNG.

The RTP simply becomes a result of the RNG which goes in any direction and cannot be attributed with having a memory. This means that it has no way of knowing the results of previous spins and as such, would not know how to influence the RTP. The two are essentially separate entities within slot mechanics.


Every jackpot slot has its fair share of symbols which are essnetially the main crux of the gameplay. These appear on the reels of a slot when a player makes a spin and the aim often is to align them in some kind of order. In doing so, this reveals wins for the player. In this way, once you have an understnding of how slots function, this visual representation makes it even esier to understand.

When you see the winning combinations and the frequencey at which they appear, it makes it easier to understand what the slot volatility and return to player might be, especially if you play over a certain period of time.

Symbols in slots can appear in all shapes and sizes and are a crucial part of the functional mechanics of the slot itself. Furthmore, the way in which every slot is programmed means that the sequence of numbers that are produced every single second by the random number generator can yield five (if a five reel slot) completely different symbols at complete random.

Because a random number generator has no memory, it is theoretically possible for a player to spin identical symbols twice in a row, however the odds on this happening would be astronomically high. There are often substantial beneifts when a player spins a winning combination of symbols meanwhile.


In slots, these have a huge influence on a player’s gameplay. A wild is known as a ‘special symbol’ which essentially unlocks potentially lucrative bonus rounds for the player, which will either reward them with sets of free spins or considerable winnings (again, this is related to an depending on the volatility level of the slot).

They are fundamentally, the highest paying symbol in the game and have been seen as somewhat of a revolutionary feature in the world of slots. It should be importantant to note though, that they do not have the power to replace scatter symbols, free spins or any other bonus round symbols.

Relating this back to the mechanics of a slot and how it works, what is interesting is that wilds are one of the rarest symbols in a slot game, though they have a high value attached to them.

Online casinos know this and also that it can mean that they may have to pay out considerable amounts, however, they are aware of the return to player rate and how this works, as well as the volatility levels and as a result, they choose their jackpot slots carefully so tht they can mitigate for any potential losses, courtesy of a high value wild.

Bonus rounds

What is perhaps interesting is whether the return to player has any particular affect on how a player can perform during a bonus round, where they will often have a number of free spins to make use of in order to unlock further benefits. These are usually in the form of more free spins or a substantial amount of cash prize winnings.

Because of the more higher stakes nature at this point of the slot game and also taking into account that it can, more often than not take quite a lot of game time to reach a bonus round, the return to player rate from this perspective is likely to become even more relevant and acute.

As such, because players have usually been through a number of ups and downs to get to this point in the game, often the return to player rate would theoretically weigh slightly more in their favour, regardless of the completely random nature of the random number generator.

Final thoughts

This guide was created in order to give you more of a technical understanding of how jackpot slots work and why they function in the manner that they do. The purpose of this is to help bridge the gap between what goes on from a technical perspective and the relationship that this shares with what occurs during the gameplay.

What can be ascertained with certainty is that the every slot is completely random based on a complete and forensic interrogation of how the random number generator is engineered from he beginning and questioning whether there is any obvious relationship between this and the slot’s return to player rate and also volatility level.

This is something that you can rest assured proves beyond all doubt that slots are in no way manipulated during gameplay and have been developed to be completely and intelligently independent.