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New players only. Min deposit $20. Bonuses up to a max of $300 + 200 bonus spins. Wagering bonus 35x. Wagering bonus spins 35x. The winnings must be wagered within 21 days. Bonus T&C apply.

The Ultimate Guide to Bonus Slots

Let’s face it - some slots seem a lot more complicated than they really are. Casino game providers like to experiment with their bonus features and give fancy-sounding names to patented slot bonuses. Don’t get us wrong - these unique and exciting game features make online slots all the more interesting. But you’re not alone if you get puzzled trying to figure out the difference between a Sticky Wild and Walking Wild.

That’s why we’ve put together this handy guide, covering all the most common kinds of bonus slots you’ll come across in your gaming adventures. From Super Spins to Cascading Reels, we’ve explained pretty much every slot bonus in the book. While new special features are introduced now and again - the following bonuses are classics that will help you figure out where the excitement lies in the most mainstream bonus slots.

Special Bonus Slots

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The Ultimate Bonus Slots Glossary Index

Deposit bonus

A deposit bonus is any bonus you receive on top of your deposit amount. Deposit bonuses can vary depending on the deposit amount, any special promotions, and whether or not it’s your first time depositing. When playing at this online casino, new players will receive a Welcome Bonus of 100% on their deposit. In other words, any first deposit will be doubled. You can read more about our Welcome Bonus on our T&Cs page. Deposit bonuses are also known as ‘reload bonuses.

Free Spins

Free spins are a wonderful thing - and exactly what you would assume based on their name. A free spin is a spin of the reel which is cost-free to you. Most slot games have free spin rounds that you can unlock through certain combinations landing on the reels. The number of free spins will always vary - some games are especially famous for offering tons of them. Occasionally, you’ll even encounter a free spins round that multiplies any wins during this round.

Free Spins

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Bonus Retrigger

A game with this feature will allow you to ‘retrigger’ slot bonuses while they are activated. If you are enjoying a bonus round, and once again the reels produce the combination under which a bonus gets triggered, then the round will start again. For example, if you were down to the last 5 out of 10 free spins, retriggering the bonus round will award another 10 free spins on top of the 5 you have left.

Bonus Retrigger

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Respin Feature

After a spin is complete, some slot games will give you the chance to ‘respin’ one single reel. This is a great feature for when you’ve just missed out on a great symbol combination. The can be very profitable if sticky wilds and other special symbols are on the reels.

Bonus Spins

When you make a deposit during certain promotions, you can also benefit from ‘bonus spins’ which are just like free spins except you are not awarded them during the game - you’re automatically given them upon depositing. For example, at PlayFrank Casino we like to give up to 50 bonus spins on great new games each time you make a deposit of $20 or more. You can also earn bonus spins by completing our Daily Challenges. Read more about our player perks on our T&C page.

Super Spins

What’s better than a bonus spin? Why, a Super Spin of course. Every so often, we’ll award you Super Spins (worth $1 per spin) on your deposit.

Expanding Wilds

If you see that a slot has Expanding Wilds - you’re in for twice the thrill. Just like a regular Wild symbol, an Expanding Wild can substitute for symbols and can appear anywhere on the reel and at anytime. However, an Expanding Wild can expand across the reel on which it appears if it could produce more winning paylines in doing so. Usually an Expanding Wild is triggered after a certain number of regular Wilds appear across all reels - but there can be other conditions for their appearance, too.

Stacked Wilds / Stacked Symbols

Stacked Wilds are very similar to Expanding Wilds, in that they fill up an entire reel to produce more winning paylines. Stacked Symbols, meanwhile, appear in the same way but they will not substitute for other symbols like Wilds do. That being said, Stacked Symbols can still drastically increase your chances of winning!

Replicating Wilds

Replicating Wilds are based around the same concept of turning more symbols into Wilds, however they appear in a different way. When a Replicating Wild appears on the reel, it will usually not turn entire reels or rows into Wilds. Rather, it will turn the surrounding symbols into Wilds.

Walking Wilds

A Walking Wild will trigger free spins while also enabling the regular Wilds bonus. When it appears on a reel, it will continue to move one reel to the left (triggering a free spin for each time it moves one step). This will continue until it has covered all reels to its left. The bonus is an exciting one that can produce some great wins.

Random Wilds

Some games include Random Wilds instead of regular wilds, whilst other combine both of these two slot bonuses in the same game. So how does a Random Wild differ from a regular Wild? They don’t - at least not that much. The key difference is that Random Wilds are a lot more, you guessed it, random! Whereas regular Wilds appear quite frequently throughout a base game, a Random Wild might only after ever certain number of spins, and often has a more powerful effect.

Sticky Wilds

This feature is most commonly activated during a free spin round. Let’s say a Wild appears during your third free spin. The Wild symbol will remain in that exact position for all remaining free spins. In other words, it ‘sticks in its position, increasing the chance for wins with every subsequent free spin.

Sticky Symbols

When a Sticky Symbol appears in a winning payline, it activates a free spin during which the Sticky Symbol stays in position. If the same symbol appears in a winning payline on that free spin, yet another free spin will be activated. This will continue until the Sticky Symbol is not matched during a spin, at which point the Sticky Symbol will disappear and the free spins will end.

Sticky Wilds

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Cascading Reels

Imagine you’ve just had the reels reveal a great winning payline. Imagine that the symbols of this winning payline explode, and are replaced with more symbols that fall from above, producing yet another winning payline. This is the idea behind Cascading Symbols - a winning payline will be replaced with random symbols which hopefully produce yet another winning payline. This feature will continue until the new symbols fail to produce a winning payline. This feature is also known as ‘Cascading Reels’ and examples include Jammin’ Jars and Gonzo’s Quest.

Cascading Wilds

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Tumbling Reels

As mentioned, some games have reels that move in an unusual manner, including avalanches, cascading reels and ‘dropping symbols’. Tumbling reels are especially awesome. After every winning combination, the winning lines disappear from the reel and get replaced by other symbols that align to make new combinations. This feature can stay active until a winning combination has been triggered again. In other words, a feature such as ‘tumbling reels’ can, in some bonus slots, ensure two wins!

Gonzo's Quest Avalanche Feature

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Rotating Reels

It can be annoying to see how narrowly you missed a great symbol combination on the reels. With Rotating Reels, the symbols will re-align in every possible way so that they result in one or several wins. With this slots bonus, you could score in every possible direction thanks to three 90 degree rotations this feature activates. Rotating Reels are crazy good in terms of maximising your chances of a win - but slot games are usually sparing in awarding them. Players can usually only enjoy this feature when playing bonus games.


Simple but amazing; bonus slots with multiplier features can seriously increase your chances of winning big. A multiplier can be activated in any number of ways depending on the slot. Often, they’re activated during a free spin or bonus round - but the conditions under which a multiplier is activated really does differ from game to game. In any case, this feature will double, triple or quadruple any wins achieved during the time it is active.

Buy a Bonus Feature

Sick of depending on luck for free spins and mini-games? If you don’t like waiting for that juicy bonus round to strike on its own accord, then you’ll appreciate the ‘Buy A Bonus’ feature. Some slot machines and online slots allow you to pay to access the bonus round. While the vast majority of bonus slots won’t allow you to skip the base game, this is still a fun bonus feature to look out for.

Gamble Feature

Certain bonus slots include an additional gamble feature, usually in the form of a fun mini-game that lets you choose from several options with a mystery reward. For example, some slots presents you with a spinning ‘wheel of fortune’ while other games boost your payout if you win a coin toss. It’s also common to see a gamble feature whereby you can correctly guess whether a card will be black or white.

Daily Jackpots

If you see that a slot has a Daily Jackpot then it’s good news for you. These bonus slots have to pay out a jackpot every 24 hours, meaning everyone who plays the slot during this time has the chance to win the big prize. Check our Red Tiger casino games for daily jackpot slots.

Progressive Jackpots

Most bonus slots will show you what the amount of the current Jackpot to be one that day, and if you’re playing a slot game which a Progressive Jackpot, then the total sum will rise as more people play the game until there’s a winner. Note that not all Progressive Jackpot slots reward daily. It is simply the case that a lot of Daily Jackpot slots are progressive.

Progressive Jackpots like Netent's Mega Fortune

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Slot players choose their games based on theme, style, win potential, habit, nostalgia or any other number of personal factors. We know that some of you, however, like to pick your online slot based on the slot’s bonuses and special features. Not surprising, considering slots bonuses can make any game twice as fun while increasing the chances of winning big. With this guide in hand, we hope you’ll never again be scratching your head at the bonus jargon in casino game reviews. Login now to PlayFrank Casino or sign up and start playing real money slot machines.

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