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Best online slots of 2021: the most popular slot machines

We all have our favorite slot machines. As creatures of habits, we tend to play these slots only. Become Gambler presents you a selection of the most popular slot machines around the world. Are you ready to explore new horizons?
Edited on 23/01/23 by Valentin MDA

Every player has his own favorite slot machines. While some prefer to play on Play’n GO slots, others are more into Pragmatic Play, Nolimit city, Booongo or Quickspin games. As we are creatures of habits, we tend to keep playing on the same games during our casino sessions.

We want to help you getting out of your comfort zone. This is why we are presenting you a selection of 15 popular slot machines from various game providers, mixed with some favorite of ours. Are you ready to explore new horizons?

Book of Dead (Play’n GO)

The first slot machine we are presenting is a really popular one that you probably already know. Book of Dead brings you to Egypt with Play’n GO’s favourite archeologist. In this casino game, you and the explorer Rich Wilde are looking for the antique Book of Dead. Your goal? Get three books in one spin to unlock the free spins feature. Good luck!


We are facing Play’n GO’s most famous and popular slot, that is broadly played around the world. With its 10 paylines and retrigger function, this slot machine really launched the “book series” both for Play’n GO and other slots providers.

Release yearRTPPaylinesFree spinsMax payout

Tome of Madness (Play’n GO)

Let’s continue with another slot from the Swedish game provider Play’n GO: Tome of Madness. Three years after looking for the Book of Dead, the explorer Rich Wilde is now looking for the Book of Madness that will allow him to unlock the secrets of the Cult of Cthulhu.


This slot machine based on H.P. Lovecraft’s fictional literary universe of the Cthulhu Mythos is a 5×5 game where you have to connect 4 or more adjacent symbols to win. You have to connect at lease 42 symbols with a single bet to unlock the bonus feature. Your ultimate goal? To unlock the Cthulhu that comes after the pre-bonus phase.

Release yearRTPPaylinesFree spinsMax payout
2019-06-2796%cluster pays™YES2,000x

Sweet Bonanza (Pragmatic Play)

We love Play’n GO slots, but there is an other provider that keeps on creating great slot machines. This game provider is Pragmatic Play. Their slots are always looking sharp and have some nice features. Sweet Bonanza is a classic game from this provider, that came out in june of 2019.


This Candy Crush looking slot machine does not work like a regular machine. It features a 6×5 board, and you have to have at least 8 similar symbols for a connection to occur (8 apples, 8 hearts, …). As soon as you have four lollipops on the board, you unlock the free spins feature. During the free spins, random multiplying bombs can fall and multiply your spin winning up to 100x.

Release yearRTPPaylinesFree spinsMax payout
2019-06-2596,51%8 symbols to connectYES21,175x

The Dog House (Pragmatic Play)

Let’s continue with Pragmatic Play. When talking about t his game provider, two slots come to mind. We already takled about the first one (Sweet Bonanza), and the second one is none other than The Dog House. It came out three months before Sweet Bonanza. 2019 was a really prolific year for Pragmatic Play in terms of creativity.


Like its name says it, this slot machine’s symbols are dogs. To unlock the free spins feature, you have to get three dog houses in a single spin. During the free spins, sticky dog houses can land on the second, third and fourth reels with a multiplier that can go up to 3x. The more dog houses you have, the higher your total multiplier is, unlocking big wins!

Release yearRTPPaylinesFree spinsMax payout

Honey Rush (Play’n GO)

Play’n GO is a really prolific provider who created a lot of slot machines. While most of them have a classic way of working, some of them pay with adjacent connections (also called clusters). Honey Rush is one of these slots.


This bee hive shaped slot machine does not have classic paylines. To get paid, you have to connect 5 adjacent similar symbols. Like on Tome of Madness, you have to reach a specific number of connections (160 here) to unlock the bonus feature. This slot’s bonus feature is the Queen Colony, where most of the board’s symbols are turned into one similar symbol.

Release yearRTPPaylinesFree spinsMax payout
2019-10-3196,50%cluster pays™NO9,000x

Book of Sun Multichance (Booongo)

We have talked about Play’n GO and Pragmatic Play, but do you know Booongo? This Ukrainian game provider creates nice looking HD games. Their games are mainly about two themes: Ancient China and Ancient Egypt. The one we present you today is about the latter.


Book of Sun Multichance is a slot machine that came out in May of 2019. It belongs to the “book” slot category, like Book of Dead and other games that came out after. Get three books during a single spin and you will unlock the free spins feature. During the free spins, getting three books will give you a retrigger (12 more spins) and unlock an additional symbol.

Release yearRTPPaylinesFree spinsMax payout

Jammin’ Jars (Push Gaming)

If you enjoy playing on Sweet Bonanza, you will absolutely love Push Gaming’s Jammin’ Jars. This slot that came out in 2018 pays in clusters of at least 5 adjacent symbols.


This fruits and jam slot machine has a maximum payout of 20,000x your bet. To unlock the free spins feature, get at least three jars in a single spin. During the free spins, the jars move around the board. Every time they connect, their multiplier increase. Connect multiple jars with premium symbols and you’re in for a big win!

Release yearRTPPaylinesFree spinsMax payout
2018-09-1896,83%cluster pays™YES20,000x

Cherry Pop (Yggdrasil)

Fruits is a recurring theme in slot machines. This one came out in October 2020, and quickly became really popular thanks to the Twitch casino streamer who played it. We are kind in a kind of love / hate relationship with this slot, especially because you have to gamble your bonus to have the maximum amount of free spins.


You start with a 5×3 board. Every connection makes the board bigger. At 5×6 you unlock the free spins feature: 5 spins that you can gamble two times to get up to 16 spins. During the free spins, your goal is to reach the maximum board size of 5×9. Once you reach this maximum setup, instead of increasing by one, your global multiplier increases by four at every connection.

Release yearRTPPaylinesFree spinsMax payout
2020-10-0696,10%up to 59,049YES56,386x

Rise of Merlin (Play’n GO)

Let’s come back to Play’n GO after this fruits slot machines intermission. Rise of Merlin is a slot that came out in June of 2019. It is themed around the story of Merlin the Magician.


It is a pretty classic slot with 10 paylines and three scatters to unlock the free spins feature. Like on Book of Sun Multichance, retriggering on Rise of Merlin grants you with an additional symbol. This slot’s maximum payout is 5,000x your bet.

Release yearRTPPaylinesFree spinsMax payout

Chaos Crew (Hacksaw Gaming)

This very slot is one of our favourites. Why? Because Vause had a 9,254x win on this machine (€1,60 bet, total win €11,931). You can see her biggest wins in our article « Vause: her biggest wins at online casino ».


Chaos Crew is a relatively recent slot machine that came out in September of 2020. This 5×5 grid game has 15 paylines and has a maximum payout of 10,000x. Get three Free Spins symbols to get into free spins mode. During the free spins, your goal is to achieve the highest global multiplier. each column has a multiplier that can be either augmented by addition or multiplication. Just try it, you will love it.

Release yearRTPPaylinesFree spinsMax payout

Deadwood (Nolimit City)

If you like high volatility slot machines, Nolimit City is a provider that is made for you. They create slots with amazing graphics and high maximum payouts. Deadwood’s is 13,950x.


With a four reels area and its 576 ways, you are in for some big wins. Get three scatter symbols to unlock the classic free spins. If you also land two sheriff badges, you get into the Shoot Out feature that is even better. Oh, and this slot also has a bonus buy option.

Release yearRTPPaylinesFree spinsMax payout

Temple Tumble (Relax Gaming)

Temple Tumble is an explosive game from Relax Gaming where connecting symbols disappear and new symbols fall into a cascade. To unlock the free spins mode, all you have to do is to clear all the blocks of the screen.


When getting into free spins mode, you can choose between three kinds of spins: multipliers & extra spins (low volatility), multipliers (high volatility), or extra spins (medium volatility). For each of these modes, when breaking t he special symbols you will either receive a higher multiplier or extra spins. This slot has a maximum payout of 7,767x your bet.

Release yearRTPPaylinesFree spinsMax payout

Reactoonz (Play’n GO)

Reactoonz is a really good slot from Play’n GO. It came out in 2018 and quickly became the favourite of a lot of players thanks to its unusual way of working. Like its prequel Energoonz, Reactoonz is themed around aliens and features a 7×7 game grid with cluster wins (5 or more aliens to connect). Every connection triggers a cascade, and opens the possibility for other connections to occur.


There is no free spins mode on this slot machine but a gigantic alien that you have to unlock: the Gargantoon. To unlock it, you have to charge the energy bar 5 times. Then, this enormous toon alien will land on the screen.

Release yearRTPPaylinesFree spinsMax payout
2018-10-1596,00%cluster pays™NO4,570x

Razor Shark (Push Gaming)

Grab your swimming gear, dive into the deep sea and pay attention to the Razor Shark. This 5×4 slot with 20 paylines is an original creation of Push Gaming.


Get at least three scatters to unlock free spins mode. During free spins, reels two and four are filled with mystery symbols that go down at every spin. Multiplier increases by one at every spin. Get the golden shark symbols and they transform into coins that multiply your bet from 1x to 2,500x.

As of now, the maximum win observed on this slot machine is 85,475x but Push Gaming states on its website that it has no maximum payout. Are you up for the challenge?

Release yearRTPPaylinesFree spinsMax payout

Da Vinci’s Treasure (Pragmatic Play)

We will finish this selection of the most popular slot machines with one we really enjoy playing: Da Vinci’s Treasure. This game from Pragmatic Play is kind of a book machine but with 25 paylines and a maximum payout of 48,000x your bet.


When landing three Cryptexes (the scatters), a Cryptex spins and gives you one of the three possible bonuses: prize picker, map quest, and progressive free spins. The best free spins mode is the progressive free spins feature. During this one, multipliers pile up, increasing by 1x at every free spin, up to 60x if you retrigger.

Release yearRTPPaylinesFree spinsMax payout
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profile author


Valentin MDA
83 articles

En tant que rédacteur web spécialisé dans le secteur des casinos en ligne, je suis à l'aise pour créer des contenus sérieux et informés, sans jamais sacrifier le ton décontracté qui rend la lecture agréable. Mon expérience dans le secteur me permet de fournir des textes percutants et authentiques, en gardant toujours à l'esprit le but ultime : informer les joueurs avant qu'ils ne se lancent dans l'aventure.

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