Slot Machines

The Ultimate Guide

Introduction to slots

This guide will teach you how to play slots like a pro. You will learn about scatter symbols, wild symbols, bonus rounds, free spins and how RTP and variance affects your wins.

Slot machines are one of the main pillars of casinos online. It is easy to understand why. The simplicity of the casino game is what makes it so easy to start playing. You win often and you may win big jackpots. The sounds and the colorful images also contribute to the overall feeling of a good time. Also there are a variety of stakes from penny machines to high stakes slots.

What are slots?

Slots used to be mechanical one-armed bandits found in every land based casino. We all have the image of how people sit with a bucket of coins and feeding the machines in order to keep the reels spinning.

Classic Slot Machine

Classic Slot Machine

Today most machines are not mechanical in nature anymore but are computer programs called video slots that simulate the very same experience. Usually there are five rows of symbols, called reels. They need to line up properly in order to win. The symbols could look like anything, fruits, aliens, numbers, letters or whatever the game creators can dream up.

Mega Big Win on Gonzo's Quest

Real Money Online Casinos

The casinos online usually promote their slots heavily. That is because they are so popular and packed with state-of-the-art features. For a relatively modest amount you can get casino entertainment for a long time. Also there is the potential big win waiting for you. At casino bonus badger you can find the best deals by adding some extra bonus money into your account upon deposit. Pick the best welcome bonus right away and skip the low value ones.

How to play slot machines?

The basics are really simple. You deposit some money and press the spin button. The reels will then spin and the game will let you know if you won or lost.

Slot Machine Spin Button

The default game settings are usually good, but you may want to change the stakes you play. One can change this in two ways, either by something called the coin value or by modifying the bet level. The combination of the two gives you large freedom to play the stake you want. The same slot can be a high stakes slot, and a penny machine by choosing the numbers that suits your play style.

When you are playing through the wagering requirement of a juicy Match bonus, there are usually limitations to how much you may bet per spin. It is rare that you are allowed to play for more than €5 per spin.

Slot Paylines – How they work

A payline, also known as winning line or betting line, is a combination of symbol positions that results in a win, on a slot machine. Only one symbol per reel contributes to the payline, so you can draw a physical line through them, hence the name.

The first slot machines only had one possible payline, the one in the middle. The winning combination needed to be neatly placed on a single straight line through the center of the slot window. The casino slot vendors soon realized that they could make people pay more coins to get additional ways of winning. Also the player gets more winning combinations, since the game now covers a lot more ground.

Today there are all kinds of payline shapes, straight, zigzag shaped or any other variation. All slot games have their own set of possible paylines. In a 5 reel slot there are 3^5 = 243 possible paylines. The game developer usually settle around 10-30 different winning lines, in order to let the player have some kind of overview.

Price per payline

The extra possible combinations come with a price however. You normally pay one coin per payline, so the stakes go up fast. If you play using 20 paylines, you also pay 20 times the stake. The benefit is of course that you will win more often, which lowers the volatility of the game.

Display of Paylines

The paylines are displayed at the edges of the screen. If you hoover your mouse over one of the numbers, it will usually light up the winning path it represents. See the example from STARBURST, which is a game with 10 different pay lines.

Paylines at Starburst Slot Machine

Paylines at Star Burst Video Slot

Some games have all the betlines active at all times. They are designed that way and you cannot change that. Other games will let you decide how many paylines you would like to have active at any point in time.

Coin value versus Bet Level – How to pick your stake on video slots

Many people wonder about the difference between coin value and bet level. They both change the total stake per spin, but in a little different way. You can start to fiddle the buttons in order to get a sense of how they influence the total stake. The machine will tell you how much you actually spend per spin.


The coin value is how much money you bet per pay line. Here you may be able to select the values €0.01, €0.02, €0.05, €0.10, €0.20, €0.50, €1.00 and €2.00. Some video slots may have a lower max, but you will get the idea.

Then you multiply this number by the total number of pay lines in the game. So if you have twenty paylines and have selected a coin value of €0.01, you will spend a total of 20x€0.01=€0.1.


The bet level is a multiplier to the total stake. In other words it changes the cost per spin. So if this is 2, you will effectively bet twice as much per spin. The bet level will give you more freedom to select the actual total stake you play per spin.

Also all winnings are multiplied by the bet level. So again, if you set the bet level to 2, you will win twice as much.

Stake per spin

By using the combination of Coin Value and Bet Level, you get a huge flexibility in selecting the stake you want. To sum up what we just said, we have the total formula for the stake as:

Stake Per Spin = Coin Value x Pay Lines x Bet Level

Example 1:

If we use Gonzo’s Quest as example, which has 20 pay lines we can chose a coin value if €0.1 and bet level 1, which gives us:

Stake = 0.1 x 20 x 1 = €2.0

Coin Value and Bet Level Example 1

Example 1, Coin Value and Bet Level gives a total stake of €2.0

Example 2:

If we set the coin value to €0.5 and bet level to 5 we would play for a total of:

Stake = 0.5 x 20 x 5 = €50.0

Coin Value and Bet Level Example

Example 2, Coin Value and Bet Level gives a total stake of €50.0

Slots Paytable

Before you start spinning find the Paytable or Info symbol, and read the basics about the game.

Slots Information Button

You should know which symbols there are, and how much cash they will pay out. Some games have special bonus rounds and a list of special symbols like WILD or SCATTER. You will also find the theoretical Return To Player (RTP) percentage, either here or by pressing the button with a question mark on it.

Again here is an example from STARBURST. The BAR symbol is worth 250 coins if you collect five in a row. The purple diamond is only worth 25 coins if you get five of those on a payline. Also you can see the possible winning combinations, and the shapes the paylines take.

Paytable and Paylines on Starburst Slot Machine

Paytable and Paylines on Starburst Slot Machine

Slots Max Bet

The MAX BET button will automatically play the maximum number of coins for one spin. This means that the maximum number of paylines is active, and the bet level is set to its max. Usually the COIN VALUE will not be affected by this.

Autoplay feature

The auto play feature is a neat functionality to have. It allows you to set a number of spins the game should make on your behalf, and you will only need to sit back and watch the results.

You can make the game play 10, 25, 50 or as many as 1000 spins in a row. Then it will stop. If you are playing through the wagering requirements of a casino welcome bonus, this is the tool for you.

In most games there are advanced settings that will allow you to set when the game will stop. For example you may want it to stop on any win, or only if you win big. You don’t want to miss the joy from that.

The auto play feature is a good auto pilot to have, but it is important to know when to use it and when to avoid it. It is an excellent feature when grinding casino bonus wagering requirements. It may also be good when hunting for big progressive jackpots, and you want spin quickly. It is not as good when you are playing for your last lunch money. They will burn quicker than you think.

First you should set up the desired number of active paylines, the coin value you want, and the bet level. The same settings will then apply for each automated spin. Next press the autoplay button and the game will play through spins over and over again. The results will show and then the next spin will start.

Monkey with Bomb

Quick Spin

In some games you can speed up the animations of the slot game. If you go to the settings menu and find something called quick spin, you are on the right place.

The outcomes of the spins are already decided through RNG, so the animations are only the eye candy that takes time. If you want to play as fast as possible, you should enable this feature.

Bonus Games

One of the popular features in modern slots is the bonus games. These are tiny games that can be unlocked during normal gameplay. In order to enter the bonus game you need to get a particular combination of symbols on the reels, such as bonus symbols, scatter symbols or similar.

Most bonus features are completely random in nature. You need to click on some item and collect the bonus behind it. Some bonuses include a skill element.

For example in the bonus game in Blood Suckers will let you open coffins to find and slay vampires. You earn cash for each vampire you find.

Blood Suckers Slot Bonus Game

Blood Suckers Slot Bonus Game

Wild Symbols

Winning combinations of symbols generally pay from left to right, with the same consecutive symbol contributing to a winning payline. However there may be WILD symbols, which are the jokers of slots. They represent any symbol, so you can get for example two sevens and one WILD to get a total of three sevens – 777. Since you generally play several paylines a wild symbol may be part of several winning paylines at once.

Scatter symbols

The scatter symbols are usually what triggers bonus rounds. They are very unique and do not need to be on any particular payline. They could be scattered anywhere on the screen, hence its name. If you find two or more there is usually a special bonus feature or special bonus prize waiting for you.

Multiplier Symbols

The multipliers are symbols like 2X, 4X, 6X and so on. As the name suggests, they will multiply your winnings. If you for example have 2X active you will earn twice the amount for each win. Not bad. Each game offers its own set of rules how they multipliers are triggered. See the slots’ paytable for instructions.

Thief Character

RTP – Return to player

Return To Player or RTP for short is what the slot will give back to the player over a long period of time. Usually it is presented as a percent, like 95%, which means that the player is expected to get back 95% of the money wagered. The remaining 5% is the house Edge, and is what makes up the Casinos’ profit.

Example: If the RTP is 98% and you bet a total of 1000$ you are expected, on average, to get 1000*0.98 = 980$ back.

If you read the rules of the slot machine, you will usually find how much it is expected to pay out. You should always aim for slots with as high payback as possible.

The casino knows the RTP of each game based on the probability of each combination to hit, together with the corresponding payouts. It is one of the design decisions a game manufacturer will set early in the game design.

The game will not adjust itself when big wins happen, or when the slot is cold. Each spin will have the same probability to hit a big win, regardless of what happened previously. The same holds true when it comes to progressive jackpots. The slot machine is not more likely to pay out the jackpot if hasn’t been hit in a long time.

Variance of slot machines

Variance, or volatility, is a measure of how the wins are distributed. Low variance means that the payouts come frequently, and are about the same size. High variance slots on the other hand means that the payouts come less often and they vary in size. You can expect long dry periods with little or no payout, however the size of the wins are usually much higher.

It is important to understand that the RTP has nothing to do with the variance of the slot. Over a long period of time, it is expected to find its expected return to the player, regardless if it comes through small steady wins, or as big wins with long dry periods in between.

If you want to play for as long as possible, chose low variance games. If you on the other hand want to feel the thrill of big wins, you should aim for high variance slots.

Piggy Riches

Ways to influence the variance of a slot machine

The slots are designed to be fun. They are supposed to get your heart jumping once in a while with catchy music and stunning graphics when you hit that big win. Each game is different and has its set of payout rules. They all have their own inherent variance, but you can actually modify it slightly on your own.

Factors that will INCREASE the variance of slots

  • Higher coin value
  • Higher coin value
  • Fewer betlines active
  • Win from left-to-right only

Factors that will DECREASE the variance of slots

  • Lower coin value
  • Lower bet level
  • More betlines active
  • Win-both-ways active

Slot machines with high variance

It is not possible to figure out the variance of the slot machine by studying the payout table only. You need to actually play the game and count how many spins that ended up winning and losing. Also you need to write down the actual size of each win. After some time you will get a feel of how the game works, and which payout structure it applies.

There are however some rules of thumb on how to spot high variance games:

  • The ratio between the highest payout symbol and the lowest is high
  • Slots with high value bonus rounds
  • Few betlines active
High variance slots
Slot Vendor
Alien Robots NetEnt
Creatures from the Black Lagoon NetEnt
Dead or Alive NetEnt
Egyptian Heroes NetEnt
Fruit Case NetEnt
Ghost Pirates NetEnt
South Park NetEnt
Sultan’s Gold NetEnt
Twin Spin NetEnt
Girls with Guns – Jungle Heat Microgaming
High Society Microgaming
Immortal Romance Microgaming
Playboy Microgaming
The Finer Reels of Life Microgaming
Thunderstruck II Microgaming
Green Gem

Slot machines with low variance

As with the high variance slots, it is not always possible to spot which games that have low variance right away. You need to play them to get a hang of the payout structure.

There are however some rules of thumb on how to spot low variance games:

  • The ratio between the highest payout symbol and the lowest is modest
  • Many betlines active
  • Win-both-ways active
Low variance slots
Slot Vendor
Blood Suckers NetEnt
Jungle Games NetEnt
Simsalabim NetEnt
Sparks NetEnt
Alaxe in Zombieland Microgaming
Forsaken Kingdom Microgaming
Machine Gun Unicorn Microgaming
Yellow Gem

Loose versus Tight Slot Machines

If a slot machine wins often it is considered to be a loose slot. On the other hand a tight machine is a slot which pays out less often. In a nutshell this is exactly what variance is about; How much a machine fluctuates around its average payout.

It does not matter if a slot machine is tight or loose with regards to its RTP. It will still pay out the expected amount over a long period of time. However if you play a tight slot machine you will usually need to wait longer before hitting big.

NetEnt Characters

RNG in video slots

The engine behind the screen is something called a random number generator or RNG for short. Basically this is a piece of software that makes mathematical calculations quickly in order to determine which combination of symbols should appear in the reals.

The algorithm actually produces pseudo random numbers, since computer software are deterministic in nature. It should not be possible to figure out the next number in the sequence. Also it should not repeat itself periodically.

There are many algorithms available to create pseudo random numbers. For example the time and hidden inputs may be used to seed the random number sequence. Even if we know the full input of the RNG algorithm, it would be almost impossible to use this information to gain an advantage over the slot machine. Today the pseudo RNG in slots are as close to actual randomness as one can get.

When you push the spin button on the slot machine, the RNG has already demined the configuration of all symbols. Before any animations or sounds have played, the video slot already knows if you won or lost. However it is certainly a lot more exciting to see those spinning reels.

Win both ways or left-to-right

The paylines usually pays out if you collect the same symbol left-to-right. So if it is a 5-reel slot game and you get 4 of the same symbols in a row on reels 2-5 you will not win anything. You would need to have the same symbol on reel number 1 in order to cash out any win.

Some games have a feature called win both ways, which will let you win by having symbols in a row starting from right or left. This feature will increase the possible winning combinations and will lower the variance of the slot.

Expanding wilds

The expanded wilds are substitutes for all symbols and will cover the entire column. In case of the slot game STARBURST the wilds may appear on reels 2, 3 and 4. They then expand to the full height of the column and trigger a re-spin. The wilds are however sticky and only non-wild reels turn, so expect huge wins when this happens.

Expanding Wilds on Starburst Slot

Expanding Wilds on Starburst Slot

Number of reels

The spinning symbols are grouped into reels. Each reel spins independently from the others. The more reels a game has, the more combinations of symbols are possible to have. This also means that it is more difficult to get the highest winning combination. You can find anything from 3-reel, 5-reel, 7-reel, up to 12-reel games.

3 reel slots

The three reel slots are what most people refer to as classic slots. They are the first online casino games that become popular among gamblers throughout the internet. Usually there are no bells and whistles on these machines. You just spin the slot and hope they hit your payline. Many people play them for nostalgic reasons.

5 reel slots

Many video slots online have five reels. The most popular casino games are 5-reel slots. The number of paylines is usually high in order to compensate for the number of possible combinations the reels can take.

Fruit Machines

The classic fruit theme has always been around. Since the early days of the one-armed bandits we have seen the fruit symbols. Fruit slots are popular in the UK but can be found on most casinos. Originally they pay out modest wins at a steady pace. This was ideal for pubs, arcades and bars.

Usually you will find a HOLD button which may stop one reel from spinning once found in a profitable position. Also the Nudge button will permit you to move a symbol slightly onto the payline.

Today you will find more advanced video slot versions of the classical theme.

Fruit Machine

Fruit Machine

Video slot machines

Basically the video slots are computers with no moving parts. In fact you see all the graphical representation on the screen. There is no physical limitation to how the reels may look like and behave; it is up to the slot vendor to design. This makes it possible to have far more creative content then their mechanical counterparts.

The online versions of slots are usually labelled as video slots.

Progressive jackpot slots

If you want to have the possibility to win really big, then slots with progressive jackpots are for you. For each coin you put into the machine a tiny percentage is taken away and added to a huge jackpot pool. Usually the jackpot increases across an entire network of casinos and machines, so it could potentially become very large.

Progressive Slots Jackpot Big Win

Jackpot meters

The players fuel the jackpot and you can see the current value on the on a jackpot meter. It is most certainly a large sign with bright colors located at the top of the slot.

Jackpot Meter Progressive Slots

Qualify to the Jackpot

It may not be enough to hit the highest paying combination of the game in order to win the progressive jackpot. It may also be required that you play for the maximum coins in order to qualify. Make sure to read the rules of each game you play in order to fully understand what is required from you.

Break-even point of the progressive jackpot

If the jackpot gets big enough a player may actually have a positive expectation for each bet. The value where this happens is called the break-event point. Keep your eyes open for big jackpots seeded by other players.

Progressive Jackpots – Are the Extra Fees Worth It?

Generally speaking, no it is not. The serious gambler should avoid the extra fee. Thousands of players however enjoy the thrill of becoming an instant millionaire, so they will always be around. Once in a while the progressive jackpot will grow big enough though. Then it may be worth considering joining the hunt for the big prize money.

3D slots

The 3D slots have a few things in common; they have excellent 3D sound and graphics. Also you will find outstanding 3D animations. The slot will come closer to an actual video game and may hook you for a long period of time. Watch out.

VR Slots

Virtual Reality slots are the latest contribution to internet slots. If you have VR goggles like Facebook Oculus Rift, you may experience your own private casino room. Playing slots in virtual reality is something completely new and takes the game to the next level.

Modern Slots 777

Online Pokies

“Pokies” is a term used in Australia and New Zeeland, and means slot. The word is originated from the poker machine and eventually become a slang word, “pokie”. There is no real difference between a pokie machine and a regular slot machine.

Bonus symbols

When playing the slots you aim for the bonus symbols. These special symbols will trigger bonus games, where you can get the best prizes in the game. They may also trigger free spins or other bonus features.

The bonus symbols often appear as scatter symbols. This means that you need to collect a certain number of them scattered anywhere on the reels. You may not necessarily need to have them on a payline in order to trigger the bonus feature.

Fruit machine hold

The old fashioned fruit machines sometimes have a hold feature. After a normal spin, the player may choose to hold one or more reels while re-spinning the remaining ones. The reels put on hold will not move throughout the next spin and it is now possible to increase the chance of a big win.

It is an interesting feature that lets the player put some skill into the gameplay. The most obvious one is when the player can lock in an automatic win. However you should also consider holding symbols that may pay out big if you manage to land the remaining ones on the pay line.

Fruit Machine Hold Buttons

Fruit Machine Hold Buttons

Free Spins during play

On popular feature in modern video slots is the free spin feature. When you play a normal spin, a certain combination of symbols may trigger the free spins. They are exactly what the name implies, spins that you don’t need to pay for. The game will play a number of times at no cost. Usually these are part of a bonus game, where you can find extra juicy prices.

Just to make it clear, these spins do not have anything to do with the Free Spins you may from a casino bonus. They are in-game features that will make the slot more enjoyable.

Retrigger free spins

When playing free spins you may be lucky enough to get even more free spins. This is called retriggering of free spins. That is a bonus within a bonus. Often the slots have limits to how many times the free spins can be re-triggered.

Cascading Reels

Some slots have an innovative feature called Cascading Reels. Basically this is the slot variant of gem-based internet games, where the winning lines will explode. The hole will then be filled by the symbols above. It is now possible to win again if the symbols fall into a winning combination.

Tumbling Reels

Tumbling reels are in reality the same as cascading reels. They provide a Tetris like mechanic, where the holes left out on a winning combination will be filled from above. New symbols will appear and you may win several times per spins.

Rotating Reels

Once the normal slot spin has finished paying out its wins, the symbols could start rotating around. The game will then check if the symbols are on a payline and give an additional set of wins. This may then continue for a few times and really big wins could be made once the reels start rotating.

Typically this feature is part of a bonus game and will not happen for standard gameplay. If you are lucky you may have locked one or two WILD symbols when the rotating starts. They will then make it easier to win additional times since they counts as any symbol, regardless of its rotation.

Rotating Reels on Video Slot

Shifting wilds

In some video slots the traditional spinning reels have been replaced with reels shifting to the right once a player hits a win on a bet line. This function offers increased winning opportunities and is really exciting.

One example is Robin Hood: Shifting Riches, from NetEnt.

Stacked Wilds

A stacked wild is essentially a wild symbol that covers more than one position. They are in similar to Expanding Wilds, but do not necessarily cover the whole reel in wilds. Different games have their own way of how the stacked wilds work, but one thing is sure, you will win a lot more once you find them.

Sticky Wilds

These are one of the best types of wilds you will find. As the name implies they will stick in its place and remain for further spins. This may create a ton of lucrative winning combinations.

Transferring Wilds

This kind of wilds usually applies when the game has more than one set of reels. Once a wild symbol has landed on the first set of reels, it may then be copied, or transferred to the second set of reels. This means that the wild symbol is used twice and big wins may come your way.

Random wilds

The difference between random wilds and “normal” wilds is how they come about. The random wilds will show up by transforming what seems to be a losing symbol into a wild symbol. This happens, as the name suggests, at random. So a missed chance may suddenly turn into a win. How cute.

NetEnt Game Character Rocket Flight

Walking wilds

This is a nice twist on gameplay. You may find wild symbols that will remain on screen between the spins. But rather than staying put, they will shift their position left to right. You will collect the wins from the wilds several times before they wonder off the screen.

Split symbols

Split symbols are symbols that may have two symbols printed on them. This means that you can get more than the natural number of symbols in a winning payline.

Free to play slots

Most of the slots could be played in free-to-play mode. You can try out new slots before depositing any money at all. The casinos may offer free to play versions of their slots directly in their slots section, and most slots vendors will offer you some free spins for play money.

At NetEnt you can play all their video slots for free.

Online Slot Themes

The early slots from the 1990s were mostly fruit machines with a single payline. The web slots found today have all kinds of themes. Here is a list of some of the popular ones.

Hollywood blockbusters

Movie themes will never grow out of fashion. You can find slots based on the latest Hollywood productions, or from old classics. The slots are themed to one or more characters in the movies and usually the art-work is impressive.

Some examples are Dracula, Planet of the Apes, The Invisible Man and Robin Hood

Dracula Video Slot

The Invisible Man Video Slot

Popular bands

Music is a theme that will attract huge audiences. There are many popular bands that have their brand on a slot machine. For example you will find games with Guns N’ Roses, Jimi Hendrix and Motörhead.

Guns N' Roses Video Slot

Motörhead Video Slot


The dirty wild west is a place where you can find gold, glory and of course bandits. It makes perfect sense to have a slot themed for this topic.

Slots with Western theme are for example: Dead or Alive or Wild Wild West

Dead or Alive Video Slot

Wild Wild West Video Slot

Common misconceptions of slot machines

If I play a slot machine and it’s not paying out, does that mean it’s due to hit soon?

No, as a matter of fact each spin is completely random. It has no memory of its previous state and each event is independent.

I just had a few near misses; the slot will compensate me and win soon.

No, that is false. Regardless if you miss by one symbol being off only by a tiny bit, or you are miles away from a winning payline, the next spin has the same probability of a win. The machine will never compensate you for being close to a win. The player will however be more likely to stay, since they think the machine owe them a win.

This is a common psychology fact as pointed out by Dr. Jon Grant at Dept. of Psychiatry, University of Minnesota.

You can read more about The Psychology of the Near Miss, by R.L Reid at Dept. of Psychology, University of Exeter, England.

Near Miss Mindset

Best tips when playing online slot machines

  • Set a budget before starting your play
  • Never chase your losses, they are gone
  • Set a time limit for your play
  • Don’t increase the bet size when you are on a losing streak
  • Never play with money you cannot afford losing

Big Slot Wins

It is always nice when slots are paying out. Here is a lucky guy who wins really big on Dead or Alive. Watch his reaction when it happens.

Big slot win on Dead or Alive

Gonzo doing thumbs up