Slot Game Bonus Features: Guide & Top Bonus Round Games

Staff Writer Editorials 2,034

Slot machine features, in the early days, were anything but what could be described as exciting.

They generally consisted of wild symbols and multipliers, and if lucky, a few would offer free spins. However, as slots progressed from mechanical to electronic, the possibilities became endless as software developers learned the fine art of creation and began to release new slot features, much to most slot lovers’ appreciation.

While not gone, those earlier slots still grace the landscape of casinos, both online and land-based and still hold value. However, for the majority of slot players, the thrill of bonus features are the big draw and the excitement that comes when triggering them and seeing the coins float across the screen as the big wins fall in place simply cannot be beaten. The list of slot features that can be enjoyed in online slots is endless it seems at times. The most popular though seem close to slot players hearts such as wild symbols, scatters, free spins, bonus games, expanding reels, cascading reels and the list goes on.

To celebrate the creative genius behind some of the best slot features, we thought it ideal to highlight those most popular, discuss what makes then advantageous in a slot and even go as far as to make a few suggestions for those online slots that include those features. We hope you find this one that makes for an interesting read, but more importantly, we hope this will help you find the perfect machine that rewards you handsomely with big win after big win!

Wild Symbols

Wild symbols are the most common bonus feature you find in slots today. The early days saw wilds being basic and only working to substitute regular paying symbols and completing wins. However, the variation of wild symbols has changed dramatically and are now found in multiple different formats. Let’s take a look at what is in store for you when it comes to wild symbols.

Regular Wild Symbol

The regular wild symbol will appear in any position of a slot machine reel and if able, will complete winning payline combinations by substituting for the missing symbol combination needed based on the paytable. Most slots will allow for the wild to appear on any reel; however, others will only be seen on particular reels such as the middle three.

Recommended Regular Wild Symbol Slots:

Spinions

Slot Developer: Quickspin

Spinions is a fantastic slot that includes wild symbols. The nice side to this slot is those wilds, whenever two or more appear become sticky and trigger a res-spin. This can lead you down a path of wild symbol delight as with each additional wild another res-spin will follow, and that only mean bigger and better wins.

The Grand Journey

Slot Developer: Microgaming

The Grand Journey offers far more than just a regular wild, oh it is there, but joining it are stacked and expanding wilds that together can collectively add up to big wins and journey to the bank!

Lost Island

Slot Developer: NetEnt

NetEnt’s Lost Island is one for the books. It not only offers a wild symbol on as part of its paying symbols but also a multiplier that can send wins to the next level. Known for its multi-wild big wins, this is one not to miss.

Hot Safari

Slot Developer: Pragmatic Play

Hot Safari will have your thirsty for wins with the heat this slot brings to the table. Its wild symbol is none other than the lion, and when it appears in the center reel, it will expand during base gameplay. However should it be found on the 6th reel, well then get ready for riches beyond your imagination?

Happy Halloween

Slot Developer: Play’n Go

Happy Halloween is a Play’n Go favourite for many a player who loves big wins and stacked wilds. Its wild comes into play during the free spins where it can appear sacked on reels two through five. If you love big win potential, this is the slot for you!

Expanding Wilds

Expanding wilds are exactly as they sound, they expand when appearing on the reels and found in a winning combination.

These are only featured in advance modern day slots and are often accompanied by animated effects. Some slots will only offer an expanding wild on the middle reel while others will be possible on all reels to allow for spectacular wins. This is especially a valuable feature when playing “ways to win” slots as it can allow for substantial wins to be achieved.

Recommended Regular Wild Symbol Slots:

Gnome Sweet Home

Slot Developer: Rival Gaming

In Gnome Sweet Gnome, the wild symbol is the female gnome and will work her wonders to match most other symbols. She even will expand and cover the full reel to help you bring in the big wins.

Incredible Hulk

Slot Developer: Playtech

The Incredible Hulk is an iconic figure in the world of comics, TV, movies, and slots. When he appears on the reel three, he expands and triggers two re-spins and may even expand onto other reels as well to award huge wins.

The Wish Master

Slot Developer: NetEnt

The Wish Master can award many wishes for those who dare ask. If you are one who lobes wild symbols, and lots of them, then this is one genie you will want to visit. The wild symbols really come into force during the free spin feature and can add multipliers, expanding wilds, stacked wilds and more. Prepare for your dreams to come true!

Boomanji

Slot Developer: Betsoft Gaming

Seldom does a slot leave you with an impression in today’s packed world of online slot gaming. In Boomanji, it is a fireworks extravaganza that will leave you filled with wonder and awe as the box of fireworks falls on the reels 2, 3 or 4 and explodes into a night of winning.

Divine Fortune

Slot Developer: NetEnt

The horse symbol acts as your wild in Divine Fortune, and what a wild it is! When it lands on the reels, it will shift one position down and continue until it reaches the last position. This can occur on multiple reels simultaneously and award some pretty impressive wins. Of course, the three progressive jackpots certainly help to keep it interesting.

Stacked Wilds

Stacked wilds are another popular variant of the wild symbol, and they work in the exact same manner as regular wilds by substituting for other slot symbols. Generally stacked wilds will be stacked three, four or five high, but in some cases, can be stacked in many other positions. Depending on the game, stacked wilds can be found on all reels or a selected number of reels.

Recommended Stacked Wild Symbol Slots:

Guns N‘ Roses

Slot Developer: NetEnt

Guns N‘ Roses is NetEnts ode to the infamous rockers that will see you in the throes of wild jubilation. The Guns N‘ Roses logo is the acting wild, and it comes in multiple forms, both as a single wild, stacked wilds, expanding wild and even as an overlay wild. Get ready to rock’n’roll with this one!

Untamed Giant Panda

Slot Developer: Microgaming

Untamed Giant Panda left its mark on the world of slots. Created by Microgaming to bring awareness to the endangered panda, it included the ability to trigger stacked wilds on not one, but all five reels, and for four consecutive spins! Add that to the free spins, and you have one slot that can bring home big wins and then some!

Neon Staxx

Slot Developer: NetEnt

In Neon Staxx, another well-designed NetEnt slot. If offers a bit of a different look that is neon-Esq and will appear in long steams of stacked wilds that, if lucky, will appear on all five reels to award huge paydays.

Secret Romance

Slot Developer: Microgaming

Microgaming’s Secret Romance is one for the lovebirds who want to celebrate their love, but it is also for those who are looking for a truly awesome slot that features stacked wilds that can appear when the mystery symbol is seen stacked on the reels.

Wolf Gold

Slot Developer: Pragmatic Play

Wolf Gold, a slot offered by Pragmatic Play has far more to offer than just stacked wilds. Joining it, you will encounter three jackpots, free spins, and a second money re-spin feature. If you love feature packed slotting excitement, this is one not to miss.

Sticky Wilds

Sticky wilds are a great variant of the wild symbol and are generally only found during free spins as a feature within a feature. When stopping on the reels, the stick wild will remain in that position for the duration of the remaining free spins. The power behind the sticky wild is that multiple wilds can form on the reels and collectively generate win after win, both small and large. When you consider that most sticky wild feature slots will allow sticky wilds on all reels, the winning possibilities can really add up.

Recommended Sticky Wild Symbol Slots:

Vikings Go Wild

Slot Developer: Play’n Go

Play’n Go is a premier provider of online slots, and Vikings Go Wild is one of their flagships games. Known for powerhouse wins, this slot features base game wilds as well as sticky wilds in the free spins. Couple that with its “Go Wild” feature that sees wilds becoming sticky and you have slot perfection.

Spinions

Slot Developer: Quickspin

Quickspin’s Spinions is one of their more known creations. Based and themed on the famous Spinions, it features regular wild symbols as well as sticky wilds. The potential for comes at the hands of the re-spin feature, triggered when two or more wilds fall onto the reels.

Dead or Alive

Slot Developer: NetEnt

One of the famous online slots powered by NetEnt, Dead or Alive has a base game wild symbol as well as a sticky wild feature during its free spins. If you like the Wild West, then it is time to get ready some gun-slinging showdown in what can return multiple five wild reel wins.

Lucky Angler

Slot Developer: Playtech

Lucky Angler is Playtech’s answer to all those who love to cast a reel, catch a few fish and win up to 205,500 coins in the process. This slot takes place on the open waters as anglers compete to find the biggest fish, joining the adventure is a sticky wild that appears on the three middle reels in both the base game and free spins.

Sam on the Beach

Slot Developer: Elk Studios

A lesser known slot developer, Elk Studios brings you Sam on the Beach, a unique and comical slot featuring a family of four living on the Big Island of Hawaii. Helping this adventurous hippie crew is four different free spin features with one that includes sticky wilds. Join Sam and the gang for a memorable vacation in the sun and win up to 227,520 coins

Roaming Wilds

Roaming wilds are a unique form of wild symbol that like the sticky wild, is often seen during free spins as an added feature. The roaming wild will see one or more wilds roaming across the reels to help achieve winning combinations. Generally, this is limited to two or three wilds but in some cases, can be more.

Recommended Roaming Wild Symbol Slots:

The Naked Gun

Slot Developer: Blueprint Gaming

The Naked Gun is a hilarious movie that is now offered by Blueprint Gaming as a video slot. The wild symbol is Leslie Neilson standing on a bullet, and when seen on the reels during free spins he will roam the reels to help lock in wins. Depending on which free spin feature, the trust detective extraordinaire can also act as a roaming wild multiplier. So buckle in my friends as you take on this crime capper!

Roaming Reels

Slot Developer: Ainsworth

Roaming Wilds, as the name suggests, features roaming wilds and is a product from the imaginative minds at Ainsworth. The roaming wilds take place during the free spins, and any wild landing on the reels will remain in play and roam around the reels. A cute and comical slot, it is one that will bring a smile to most player’s faces.

The Invisible Man

Slot Developer: NetEnt

NetEnt’s The Invisible Man is a branded slot based on the famous television series of the same name. It includes two roaming wild symbols; one is a police officer, the other a bank robber. The two symbols can appear individually or simultaneously and are featured during both base game and free spin action.

Goldilocks and the Wild Bears

Slot Developer: Quickspin

A video slot released in 2017, Goldilocks and the Wild Bears offers not only a regular wild symbol but a multiplier wild as well. Based on the childhood nursery rhyme of a similar name, it affords you the change at five of a kind multiplier wilds, free spins and more!

Random Wilds

Random wilds are less common but have some good value. They generally are triggered by a particular symbols landing in a specific location on the reels, such as the middle reel. When triggered, a number of positions on the reels will randomly be turned wild to help complete payline wins.

Recommended Random Wild Symbol Slots:

Razortooth

Slot Developer: Quickspin

Quickspin’s Razortooth is a cool slot that has a jungle theme. As you spin the reels, at random the Razortooth saber may leap across the reels leaving a trail of wilds in its path. This is a base game feature and cannot be triggered during the free spins.

Thunderstruck

Slot Developer: Microgaming

Thunderstruck is one of Microgaming’s more powerful slots. It features a random wild feature that can turn one to five reels into stack wilds. The winnings can really stack up in this slot and is well worth a few spins.

Fat Rabbit

Slot Developer: Push Gaming

Fat Rabbit is one of those slots destined for greatness, and that is thanks to its shifting wild symbol when playing its free spins. Each time a carrot falls onto the reels, the rabbit will mosey over, eat the carrot, expand and continue until it fills the screen should it eat enough carrots. This is a big win game and one not to miss out on.

Volcano Riches

Slot Developer: Quickspin

Volcano Riches uses random wilds in a slightly different way but meets the definition. When the stacked wild appears on the middle reel, it will erupt and fire off multiple wilds into the air that will be placed randomly to on the reels. The result can see you winning up to 1250x your bet!

Wild Crystal

Slot Developer: Playson

Wild Crystal is a uniquely constructed slot that offers colliding wilds that come courtesy of the wild symbol that will shift to other positons on the reels and help you to complete wins, If the wild arrows collide, then you can win up to 25x the payout!

Shifting Wilds

Shifting wilds are another form of wild that will be seen as a feature within a feature. When active, wilds appearing on the reels will shift one position, usually to the left to help achieve wins. However, in some cases, a random number of shifting wilds will be added to the reels and shift with each free spins. The nice side of this style of wild is it allows for multiple wilds to appear simultaneously and therefore trigger multiple large wins.

Recommended Shifting Wild Symbol Slots:

Dolphin Cash

Slot Developer: Playtech

Dolphin Cash is a Playtech slot that featured a fun-filled adventure into the playground of dolphin. When the dolphin wild symbol appears on the fifth reel, it will move one spot to the left until it gets to the first reel where I will exit the reels.

Robin Hood: Shifting Riches

Slot Developer: NetEnt

Robin Hood: Shifting Riches, a NetEnt production offers a shifting reel feature that whenever a win is completed, the reel on the farthest right will be replaced with a new reel.

Wild Toro

Slot Developer: Elk Studios

Wild Toro will have you ready to call out “OLE” when Toro appears. This brute of a bull is here to give you plenty of excitement and will move to the left whenever appearing in any position on the reels.

Ghostbusters

Slot Developer: IGT

Ghostbuster is an IGT engineered slot that features slimming wilds, appropriate when you consider its theme. When the Slimer or Marshmallow man appears, they can become wild and will slimmer across the reels to help generate wins.

Man of Steel

Slot Developer: Playtech

Man of Steel is a progressive jackpot slot that features shifting wilds when either Superman or General Zod land on the reels. Superman moves to the right while Zod heads to the left. If they collide, a battle will be played out on the reels to award wins.

Multiplier Symbols

Multipliers are always a hit with slot players, and for a good reason. It does not take much imagination to understand their role in a slot machine, and with multipliers starting at 2x and increasing up to 100x, those slots that include them can deliver some serious winning action.

Recommended Multiplier Symbol Slots:

Bridesmaids Online Slot

Slot Developer: Microgaming

Bridesmaids is an adaption of the famous movie of the same name. Its multiplier symbol comes into play during one of its many free spins bonuses and will multiple wins based on consecutive wins. For the lucky slot player, up to 525,000 coins can be won!

SteamTower

Slot Developer: NetEnt

NetEnt’s SteamTower has received much fanfare since its release. When entering its free spins as you climb the tower, your multiplier increases up to a maximum of seven. Make it to the top of the tower and a special bonus will be yours!

Alaskan Fishing

Slot Developer: Microgaming

Alaskan Fishing takes you deep into the heart of wild Alaska where you are on a fishing trip alone in the wild. Enter its fishing bonus game and reel in a big one to see your bet multiplied by up to 100x!

Pearls of India

Slot Developer: Play’n Go

Pearls of India is a nicely put together slot that offers you the chance to cash in on those elusive pearls women love to wear. When its cascading symbols come into play, you can see yourself going home with up to 10x your win!

Scary Rich 3

Slot Developer: Rival Gaming

Scary Rich may not be that scary, but its big wins can certainly make you jump! The werewolf is the multiplier symbol to watch for, and it multiplies your bet by up to 10x when three or more appear!

Free Spins

Free spins are, next to wild symbols the most prevalent slot features in modern slots. The number of slots that feature free spins is staggering and can come in many different styles including those that add a multiplier to free spin wins, extra bonus features and even features within feature free spins.

Recommended Free Spin Slots:

Danger High Voltage

Slot Developer: Big Time Gaming

Danger High Voltage is a popular slot from Big Time Gaming that features free spins with sticky wilds and multiplier symbols that can range as high as 66x.

Immortal Romance

Slot Developer: Microgaming

Immortal Romance is one of Microgaming’s more popular slots, one for its vampire theme, and two for its free spins. The free spins offered include four different combinations, each with its unique feature within a feature. With a top win of $72,900, the opportunities are endless.

Rich Wilde and the Book of Dead

Slot Developer: Play’n Go

Rich Wilde and the Book of Dead took the world of slots by storm when released. This slot offers wild symbols and a unique free spins feature that selects one expanding symbol as a scatter during free spins. This allows for five of a kind wins on all paylines and some serious wins to accumulate.

Wolf Run

Slot Developer: IGT

Wolf Run is not only a popular slot in land casinos but also online, and playing it gives you a chance at legendary big wins thanks for its free spins that include stacked wilds and the possibility of retriggering!

Book of Ra

Slot Developer: Novomatic

Book of Ra is one of those you soon do not forget. Triggering its free spins can see you off to the stratosphere of big wins. This is thanks to one selected symbol taking on the role of the scatter and the possibility of full screen wins.

Cascading Reels

Cascading reels are a recent addition to the many other slot features and is one well-received by slot players. Those slots that include this feature will see symbols exploding or disappearing to allow new winning combinations to be formed on the reels, and for some, this can be continuous and even include a progressive multiplier on the amounts won!

Recommended Cascading Reel Slots:

Power Spins – Nuclear 9’s

Software Developer: Microgaming

Power Spins – Nuclear 9’s may call this feature rolling reels, but it is essentially the same thing. Each time a win occurs the symbols will disappear and make way for new symbols to take their place. This continues until no new wins materialise on the reels.

Sugar Pop

Software Developer: BetSoft

Sugar Pop, a fun slot from Betsoft offers a sweet tooth a day of fun. Each time you find those tasty candies lining up on the reels, they burst and allow others to take their place. The more sweets you get, the greater the rewards that follow.

Cricket Star Online Slot

Software Developer: Microgaming

Cricket Star is a cricket players dream, and while it has multiple features, in this example we focus on its rolling reels feature, which is identical in nature to cascading reels. Each win means new symbols will follow in their place to try to achieve new wins

Energoonz

Slot Developer: Play’n Go

An excellent slot from Play’n Go, Energoonz will leave you electrified with big wins thanks to its cascading reels feature. This comes into play with each win and continues until no other wins fall into place.

5 Pyramid: Quest for Immortality

Software Developer: NetEnt

Pyramid: Quest for Immortality is a NetEnt powered slot, and as one knows, NetEnt is serious about big win slots. Its cascading reels feature can see blocks up to 5×3 cascading from its reels to be replaced with new symbols and the potential for a big win. This is one pyramid scheme you will not want to miss!

Re-spins

Re-spin slots are always an exciting feature for slot players. There is nothing like hitting a nice win only to know that the reels will spin again and potentially award you not only a win but maybe even some more re-spins as you move towards the big wins. While not as common as many of the features discussed, there are still some great online slots that feature re-spins.

Recommended Re-spin Slots:

Phoenix Sun

Slot Developer: Quickspin

Phoenix Sun is a unique slot in that with each winning combination; the reels will re-spin to allow for greater wins. This continues until no new wins are formed on the reels. It also allows for new ways to win to become available and the possibility of triggering the free spins.

Reel Rush

Slot Developer: NetEnt

Reel Rush is a NetEnt slot that offers not only a unique reel set but also a re-spin feature. Each time a win is formed, the reels re-spin to allow for new wins to take their place. With each win that follows, the number of available paylines increase. After seven consecutive re-spins, free spins will be triggered and will include the re-spin feature.

Popinata

Slot Developer: RealTime Gaming

Popinata is an RTG creation that includes a valuable re-spin feature that triggered with any win that includes one or more expanding wild symbols. If another expanding wild appears, a second re-spin will take place, with the maximum number of re-spins being three.

Starburst

Slot Developer: NetEnt

Starburst offers a re-spin feature whenever one or more expanding star symbols appear. Up to three re-spins can be triggered, and the results can “take you to the moon” if you will.

Jack and the Bean Stalk

Slot Developer: NetEnt

When it comes to re-spins, few others match NetEnt’s Jack and the Bean Stalk. Offered during the free spins, each time a wild symbol appears on any of the reels it will trigger a re-spin, the nice side to this is as you collect key the wild symbol will increase to include double wilds and full reel wilds. The possibilities are endless, to say the least!

Bonus Games

There are few slot players who do not love a bonus game. These often are the ticket towards hitting the big wins, let alone are entertaining to play, whether in their basic form or those that are ones with multiple levels.

Bonus games come in several ways, they can appear on the reels or will send you to a bonus screen where the bonus game will be played out. Many include special storylines based on the slots theme and will include player participation in order to advance and win the big prize.

Recommended Bonus Game Slots:

Vikings Go Berzerk

Slot Developer: Play’n Go

Vikings Go Berzerk is a unique creation when it comes to its bonus game as multiple variables can come into play. Its bonus game includes sticky wilds that can provide the ability to fill all slot positions with wild symbols and some substantial wins to be realized.

Fruit Warp

Slot Developer: Thunderkick

Fruit Warp is without a doubt a unique game, both in its bonus game and its design. The bonus games takes effect when five or more of the same symbols fall into view. This will trigger a res-pin feature that will continue until such time as no other triggering symbols are seen. With each winning combination during the re-spins, it is possible to increase the multiplier to award huge wins.

The Wild Chase

Slot Developer: Quickspin

The Wild Chase offers a free spin bonus game that includes a sticky wild and multipliers up to 5x. Upon three bonus symbols appearing, ten free games are triggered.

Sweet Alchemy

Slot Developer: Microgaming

Sweet Alchemy offers a unique Super Meter base game bonus that when filled unleashed extra wild symbols onto the reels and can also extra wilds of differing kinds. Watch your sweet tooth in this one!

Wild Seas

Slot Developer: Elk Studios

If you are one who enjoys a day at sea, then Wild Seas will satisfy your craving and do so in style thanks to its Break the Convoy bonus game. Captains, Pirate ships wilds symbols all come together in one massive explosion of winning!

Progressive Jackpots

Progressive Jackpots have come far in recent years. Gone, for the most part, are the days when jackpot slots required larger bets as today’s progressives allow even minimum bet spins the opportunity to go home a big winner.

With each spin of the slot, a small portion of the amount staked goes towards the jackpot until such time as the jackpot has been triggered. Many of today’s progressives also are triggered randomly and come in both network and standalone versions.

Recommended Progressive Jackpot Slots:

Mega Moolah

Software Developer: Microgaming

Microgaming’s Mega Moolah was the first progressive slot machine online to offer a top jackpot of at least $1 million. It features not one, but four progressive jackpots that are triggered at random. This takes you to a bonus wheel where one of the four jackpots will be won.

Mega Fortune

Slot Developer: NetEnt

NetEnt has the proud distinction of claiming the largest progressive jackpot win in history online. That win came in at a respectable 17.8 million euro after its bonus game triggered the Mega Fortune wheel bonus. The game includes three progressive jackpots and in a three staged bonus wheel that offers the chance to win one of the progressive jackpots of a cash prize.

Good Girl, Bad Girl

Slot Developer: Betsoft

Good Girl, Bad Girl is a take on those two little friends that call our shoulders home. The good and the bad, it features two progressive jackpots that can be won when you enter the Money Wheel Bonus game.

Divine Fortune

Slot Developer: NetEnt

Divine Fortune is rather interesting in so far as it features three progressive jackpots and is a Roman Empire themed slots. Collect three bonus symbols, and you will enter its bonus game where you have a chance at a coin prize or walking away with one of the progressive jackpots!

 

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