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An Expert Guide to Slot Bonus Features

This guide will be a run-through of all the different bonuses that you are likely to find in newly released slots.

Introduction to Slot Bonus Features

Slots were invented at the turn of the 20th century and for decades they followed the same basic system of reels and symbols (read our article on History of Slots). A lever was pulled, wins were awarded when 3 matching symbols appeared on the middle row and that was all there was to it.

The introduction of video slots changed all this and nowadays with thousands of online slots being released every year it becomes increasingly difficult for slot designers to make something that stands out from the crowd. Not only do slots now need to look incredible but they need to offer a bonus that is exciting and if possible, unique. Read on for an overview of the unique bonuses you can expect to find when you play online slots.

Introduction to Slot Bonus Features

What is a Bonus?

A bonus is a game within a game. The main game, or “base game” as it is normally referred to, is the standard set of symbols, reels and paylines as described in the pay table. The base game is where you have the chance to land standard symbol combinations and this is normally where you will trigger the bonus game. The base game is the one you begin playing on your very first spin of the reels.

A bonus game is any additional game that you trigger via the base game. In most cases free spins and jackpots are categorised separately from bonus games, but the principle is the same, in that they exist outside of the base game and once they are triggered they don’t cost any more to play.

In most instances a bonus game will result in a guaranteed win and more often than not triggering a bonus game is an absolute must to have any hope of walking away from a slot with more money than you started playing with.

Triggering Bonuses

To trigger a bonus is to activate it and there is one very common way that this can be achieved. Normally, when you trigger a bonus you need to land 3 or more of a particular symbol anywhere on the reels in a single spin. In some instances you will only be able to land 3 of those symbols. In fact, in some instances there will be reels that are designated as those on which bonus symbols can land. For example, in a 5-reel slot you will often find that bonus symbols can only land on reels 1, 3 and 5.

Sometimes these triggering symbols will come with a monetary value and more often than not they will pay out even if they do not land as part of a payline. These symbols are referred to as scatter symbols.

In other slots you will need to collect certain symbols that are normally added to a meter of some sort. Once you have collected enough symbols to fill the meter you will see the bonus triggered. This method of triggering the bonus is less random than others, as you can see the progress you are making as you collect more symbols. [Note – this type is regularly excluded or limited when it comes to promotional incentives offered by the casino, so be careful if you are playing this format of slot game while engaging with a promotion.]

However, one thing to be aware of is the added allure of continuing to play beyond your budget as the meter begins to fill. It is human nature to not want to give up on something once you begin to see progress being made. This is an obvious attempt by the designer to keep you engaged and spending money when you should be walking away. Our advice is the same as ever, in that you should stick to your budget regardless of how close you think you might be to triggering a bonus.

In slots that come with cascades or rolling reels you will sometimes find that you are required to land a certain number of consecutive cascades in a row before the bonus will trigger (we'll discuss these features shortly).

In slots that have more than one bonus then you may have multiple ways in which those bonuses can be triggered.

There are also bonuses that can trigger within bonuses. Certainly, in many games it is the triggering of an initial bonus that drags a seemingly dormant game into life.

Essentially, what I am trying to make clear here is that there are many different ways that a bonus feature can be triggered. There are likely to be methods I have not mentioned and there are likely to be methods that will pop up in the future that we haven’t seen before. However, the common way to trigger any bonus feature is with 3 matching scatter symbols.

Regardless of the slot, you should be provided with clear guidelines as to how the bonuses triggers in the paytable, something that is always worth checking out before you begin playing.

Bonus Buy

An increasingly common way for a player to trigger a bonus is through a Bonus Buy option, when you buy the bonus and then hope that you can win back more than you paid out to play it. These options often offer a more attractive RTP than the main game.

Bonus Buy options are not available in all jurisdictions, the obvious exemption being the UK, where it is deemed that paying for bonuses is too dangerous and too much of an initial outlay. Essentially, authorities in the UK see paying out 60 to 80 times the bet in one go as too much to spend on one single bet.

In fact, despite offering improved RTP figures, due to the requirement to bet at a far higher level than the main game, the improved return for players is more than offset by the increase in wagers resulting in Bonus Buy features by and large being far more expensive for players than the standard game. This is discussed in our article, 'Slots Bonus Buy Features - What Do They Really Cost?'.

So, for those who can, why use the pay to play Bonus Buy features when the cost is very high? The main reason would be that you are cutting out the middleman. With Bonus Buy features you forego repetitive base game play that can be a little dull. But if you do choose to engage with these features, know that you will be paying more for your entertainment - even with the increased chance of bigger winnings and the improved overall RTP - that you would be betting the equivalent stake on the main game.

Here is our advice:

You have to budget. You have to lay out how much you want to wager on slots and you must stick to it. If you wager an equal amount on the main game or the Bonus Buy feature, the Bonus Buy feature would be expected to cost you less. The problem that many find is that this wager budget can disappear very quickly if you want to use pay to play a bonus. This can often mean that the half hour you have set aside to play slots still has 20 minutes to run by the time you have spent your wager budget. If you find yourself struggling to walk away once your budget is gone then Bonus Buy features are not for you. If you play on, any potential savings that you might expect from the improved RTP rapidly disappear.

Remember, Bonus Buys are fun because you get straight to the exciting parts of a slot without having to trudge through all the boring bits. This is the upside. The downside is that you can find your budget disappearing very quickly, which makes it even more difficult to walk away when your budget is gone.

Always check to see how much it costs to trigger pay to play bonuses because there are some out there asking far too much, that all but guarantee the player failing to recoup that initial outlay. Anything asking for more than 80x the bet is rarely worth the entertainment that it brings.

Types of Bonus Games

Pick ‘n’ Click

The most common type of bonus game is the pick ‘n’ click. A revelation when first introduced, pick ‘n’ click bonuses are now something that every slot player will be familiar with. They normally consist of a number of symbols or objects being displayed and the player being asked to select one or more of them to reveal prizes. A common variation of this will display an even number of identical symbols, such as the reverse of a playing card, and your job is to flip them over 2 at a time until you reveal a matching pair. Whatever monetary value is found on these matching symbols will be rewarded as an instant cash prize.

Whilst matching pairs is a common version of pick ‘n’ click bonuses there are plenty of other types that you can find too. However, the one unifying factor will always be that you have to click on random symbols in an attempt to unlock a prize.

In most instances, the amount that can be won will reflect the amount spent on the triggering bet. In other words, the higher the value of the triggering bet, the more you can win during the bonus.

As with all bonuses there can be a few differences between pick ‘n’ click games that you should be aware of. Not all pick ‘n’ click bonuses guarantee an instant win. In some cases there will be a reveal that sees you leave the bonus with nothing. Some will reveal prizes other than cash, like free spins.

Additionally, in some instances, once you have revealed a win you may have the chance to pick again. If that is the case then you may find there are combinations that end the bonus prematurely, but at the same time it may be possible to collect multiple cash prizes.

You may also find that pick ‘n’ click bonuses can reveal level advancements that take the player to a new game where bigger prizes are made available.

Something else worth noting is that with improvements in technology you may find that pick ‘n’ click bonuses involve more than just flipping over some playing cards. There may be doors to walk through or directions to go in, but regardless of how exciting this looks or feels you are still picking and clicking.

Bonus Wheels

Another very common type of bonus is the bonus wheel. Bonus wheels are made up of different sections – similar to a Roulette wheel - and each section is given a value of some sort. It could be a monetary value, it could be a jackpot, it could be additional spins or it an advancement to another wheel with more impressive rewards. There is even the chance that a bonus wheel will give you the opportunity to trigger another feature.

Normally these bonus games are over quickly, following a single spin of the wheel. Whatever it lands it on is what you walk away from the bonus with. However, in some instances you are given multiple spins of the wheel and a chance to win more than one prize.

Free Spins

Free Spins are such a popular bonus that they are an entity all of their own. When evaluating the quality of a slot game many reviewers will look for the inclusion of a bonus and for the inclusion of free spins separately, even though free spins are just another bonus feature.

Free spins are normally triggered by landing 3 or more of a specific symbol. If the slot comes with a standard bonus then you can expect the triggering symbol for the free spins to be different to that of the standard bonus. More often than not, the symbols will not need to land on a payline in order for the feature to be triggered.

Additionally, instead of a payout, sometimes you will find that the number of free spins symbols that you land will correspond with the number of free spins that you are awarded. For example, 3 symbols may gain you 10 free spins, whilst 4 may get you 15 and 5 may get you 20.

Each of your spins will play at the value of the triggering bet. In other words, the higher the risk, the greater the reward. However, never forget that triggering a free spins bonus can take a long time and as such a budget should always be considered before playing, regardless of the potential that a free spins bonus holds.

Free spins are, as the name would suggest, free, which means that once they are triggered you will not have to spend anything during the feature.

Sometimes free spins can be re-triggered, which means that there is a chance that you can be awarded additional free spins during the feature. This is normally done in the same way that they are triggered in the first place.

Free spins can also come with additional features that do not exist in the base game. For instance, you may find the inclusion of wandering or expanding wilds. You may find that mystery symbols are introduced or even an entirely new set of reels, symbols or perhaps even both.

Free spins are one of the most important features in any slot. They are more entertaining than most bonuses because they last longer and you know that once they are triggered everything that you earn within those spins is being won at no additional cost. A slot without free spins is often a very difficult one to recommend and as such free spins are a key factor in determining whether we think a slot is worth playing or not.

Cascading Reels/Rolling Reels

Another common bonus feature differs from the triggered bonus features we've been discussing above. Cascading, or Rolling Reels are a bonus feature that is present in the main game. This would be considered a bonus feature by most players as it fundamentally changes the way the reels work. The player spins the reels as normal, but once the reels stop if there are any winning combinations the combination is paid then the symbols that contributed to the win will be removed from the reels. This allows the symbols above to drop down to fill the spaces and new symbols to fall in from the top of the reels. This process is then repeated, continuing until no new winning combinations are formed.

This feature is often combined with other bonuses, like increasing multipliers based on the number of consecutive winning combinations or free spins or other bonuses triggered by consecutive winning combinations.


Along with free spins some of the most popular bonuses you can find are jackpots. They are essentially 1 large payout that exists outside of the base game. Normally there are different amounts that can be won with the top prize being the least likely that you can win and as such the one everyone wants the most.

Jackpots can be difficult to trigger in the first place but if you can manage to do so they will often be the difference needed to walk away in profit.

The amount you can win in any jackpot is normally related to the size of your bet. In other words, the more you risk on your standard spin, the more likely you are to win big in a jackpot.

However, as alluring as a jackpot may seem, you must never factor a jackpot win into your spending. If you win then see it as the bonus that it is but do not raise your bet beyond your means just to land a bigger jackpot that may never see the light of day.

The basic jackpot will not change in value, except when you change the amount that you are betting on each spin. The value of the jackpot will relate to the amount you spend. Obviously, the more you are willing to risk on your spin the larger the jackpot you can win.

There will quite often be a number of tiers of jackpot – mini, mid, high for example – and the different tiers can be awarded by different in game events, including receiving specific combinations of symbols, perhaps paired with a specific payline, within a bonus feature or even simply randomly on a spin regardless of the results or the actual spin.

Progressive Jackpots

Progressive Jackpots

Progressive Jackpots see the value of the Jackpot increase as more people spend money playing the slot. The value of the Jackpot can be huge, making progressive jackpots a massive draw for many slots players. To learn more about how this works, see our article Online Slot Payouts Explained.

One thing to be aware of is that when looking at slots containing progressive jackpots the RTP figure can be misleading. The jackpot payouts are so large for the winner that other players have to have a far lower return to allow the game to average out at the RTP figure. While this dynamic is present in all slot games, it is exaggerated in Progressive Jackpot games and means that you are less likely to win with each of your spins than with other slots, with the payoff being the chance to land that huge jackpot. You can learn more about RTP figures in our article Online Slot RTPs Explained.

The other big issue that you may encounter when playing a progressive jackpot is that it may only trigger when you play with the maximum stake available. This is most likely to be a very sizeable sum of money, one that most people will struggle to find room for in their budgets.

There are two basic types of Progressive Jackpot:

Local Progressives

With local jackpots the size of the jackpot will increase as more people spend money on that slot. The jackpot will only be increased via the amounts spent at a single casino or small group of casino. In other words, the amounts added to the jackpot you are playing at will only be contributed to by others playing at that casino.

Network Jackpots

Network Jackpots will see that value of the Jackpot increase through bets placed by anyone playing that slot via any casinos regardless of ownership.

Regardless of the amount that can be won on a jackpot, we do not advocate that you alter your approach to playing slots. Budget both time and money regardless of the size of the jackpot on offer. Only play at maximum stakes if you can afford it or if you are happy for the time you have put aside to play slots to be over very quickly.


The bonuses that a slot offers will often determine whether or not we would recommend that slot. A good bonus shouldn’t be defined by the amount it can win you (because there never any certainties with this) but by the entertainment it can bring.

Our philosophy on slots has always been that there is no way to cheat the system, that you are less likely to win than you are to lose and that there is no way to purposefully defy those odds. Triggering a bonus will give you a better chance to walk away with a profit but there is no way to guarantee that trigger will happen within the time frame and the budget that you have set aside to play.

If slots are a form of entertainment then we want bonuses that are entertaining. The more fun and engaging that a bonus is, then the better the slot.

Advancements in technology have meant that slot bonuses are becoming an art in themselves, not just in terms of their aesthetic but also in terms of the game play that they can offer. For this reason it is impossible to list every type of bonus as some are entirely unique to the slot they appear in.

This sort of ingenuity is exactly what we ask for when trying to define what makes a slot worth playing. We will never suggest that slots can be beaten, that bonuses can be exploited or that you can get one over on the casino, because if we did do that we would be selling a lie.


A slot bonus is any game that exists outside of the base game.

Yes, as they exist outside of the base game free spins are a bonus. However, free spins are such a common type of bonus they are more often than not categorised individually.

Strictly speaking a bonus should not cost anything, beyond what you spend playing the base game to trigger the bonus. However, some can only be triggered if you play at maximum stakes, some can be triggered through a “Bonus Buy” option and a very small minority will require additional funds.

No. There is no way for players to beat the bonus. You may have to make certain decisions about how to play a particular bonus. For example you may have the option to play with fewer free spins with additional wilds, meaning you have fewer spins but a greater chance to win on each spin. However, there is rarely a right or a wrong approach to make when making these decisions. Certainly there is no way for you to make an informed decision that will give you an advantage over the house.

Yes a Jackpot is a bonus.

We cannot answer this question for you. You have to look at your own budget and decide what you can afford to lose before you begin playing. Once that budget is gone, you have to stop. If you find that budget running out prematurely, then it is arguably not worth you playing at maximum stakes for the chance to trigger a progressive bonus.

There is no obvious answer to this question as it all comes down to a matter of choice. We always like to see free spins and jackpots and if you can find a slot with both then chances are we will recommend it.

A jackpot is a lump sum win that exists outside of the base game.

The outcome in a bonus is random, but you may find that the chances of hitting a large bonus are less than the chances of hitting a smaller one. Certainly, in terms of a Jackpot you are always more likely to hit a smaller jackpot. Additionally, as much as the outcome is often determined as soon as the bonus begins, it doesn’t change the fact that playing through the bonus can bring entertainment.

Bonus Buy features give send conflicting messages to players. On one hand they require a far bigger than standard bet to trigger. On the other they usually offer a better RTP than the main game. The truth is that the bigger bet normally more than offsets the improved RTP, meaning that Bonus Buy features cost more for players to play than the basic game.