Book of 99 is an entertaining Greek mythology-themed slot with huge winning potential. This high variance slot has a mammoth 99% RTP, which is higher than almost every other slot you'll find and is enough to catch the attention of even seasoned slot gamers.

With Wild Scatters and Free Spins features, both of which involve a random Expanding Symbol, there's a lot to love here. Read our review to learn everything you need to know about this epic Relax Gaming slot.

The Best Casinos to Play Book Of 99

How to Play Book Of 99 Online

Book of 99 is a Greek mythology-themed slot with five reels, three rows, and 10 static paylines. The game revolves around its Free Spins, which like any other slot with a title starting "Book of…" includes a special expanding symbol. To keep things interesting, this feature is triggered the conventional way, and through the scatter meter at the side of the screen.

The graphics and animations are simple, familiar, yet beautifully executed. Relax Gaming is known for crisp, eye-catching graphics and that skill means even the relatively generic imagery of Book of 99 still stands out against the wide range of similar online slots that are available.

Info icon Basic Info
Type: Video Slot
RTP: 99%
Developer: Relax Gaming
Highest Jackpot: £500,000
Mobile Friendly: Yes
Info icon Features
Free Spins: Yes
Multiplier Bonus: No
Gamble Feature: No
Info icon Layout
Reels: 5
Rows: 3
Paylines: 10
Volatility: High
Theme: Ancient Greece
Info icon Settings
Autoplay: Yes
Adjust Paylines: No
Highest Payout: 5,000x
Minimum Bet: 10p
Maximum Bet: £100

Before spinning the reels of the Book of 99 online slot game, players need to choose a bet amount between the minimum of 10p and the maximum of £100 per spin. With fixed paylines, there will always be 10 in play so once the bet amount is set it's ready to go.

With a higher volatility than most slots, this is a game that will suit high rollers who have the budget to wait for the big wins. However, the low bet minimum means that players with smaller budgets can try their luck here too, and with a 99% RTP, who knows what'll happen?

Book Of 99 Slot
Book Of 99 Slot

How to Win at Book Of 99

Wins in the base game of Book of 99 happen the conventional way. Land three or more matching symbols on a payline (two in some cases) to secure a win. The Scatter Wild symbol (which is the book) can also help with winning combinations. As it is also the scatter, the wild will substitute for all other symbols, hence making winning combinations easier to land during both the base game and the bonus round.

The jackpot potential comes in the Free Spins feature thanks to the expanding symbol (although it is technically possible in the base game). If all reels are filled with the highest value symbol (The Greek Hero) then the 500x stake win for five of a kind will occur on all 10 paylines, giving a 5,000x bet payout.

If you're playing the maximum of £100 per spin at this point, then the highest possible win is a staggering £500,000, which is a life-changing sum for anybody.

Book Of 99 Pay Table & Paylines

Basic Info 2 Symbols 3 Symbols 4 Symbols 5 Symbols
Greek Hero Greek Hero 1 10 100 500
Sorceress Sorceress 0.50 4 40 200
Ogre Ogre 0.50 3 10 75
Harpy Harpy 0.50 3 10 75
Ace Ace - 0.5 4 15
King King - 0.5 4 15
Queen Queen - 0.5 2.5 10
Jack Jack - 0.5 2.5 10
10 10 - 0.5 2.5 10
Wild

Wilds substitute every symbol except Scatter

Paylines Paylines

RTP & Volatility in Book Of 99

The return-to-player percentage (RTP) of a slot game is the average payout expected over infinite theoretical spins. While a good way of judging a slot's generosity, the RTP should not be considered a guarantee of a game's payout habits.

The remarkably high RTP of 99% ensured this slot made a quick impact amongst online slots fans. That means the slot will (on average) pay £99 for every £100 wagered. With the expected RTP of online slots being around 95-96%, this Relax Gaming slot is well above the industry standard and therefore provides big win potential.

RTP and Volatility in Book Of 99 slots Graph

While the RTP of a slot focuses on what it pays out, the volatility (or variance) focuses on the how. A high volatility slot may have long waits between payouts, but pays big when it does. Low variance games will reward players little and often. Again, this is an average and not a guarantee.

Book of 99 has extremely high volatility, which means players with a large enough budget and patience to play an extended session are most likely to win big here. There's no pattern due to the random nature of the slot. One day the jackpot may hit on its second spin, the next it can eat up your bankroll, with no wins at all.

How Does Book Of 99's Winnings Compare to Other Slot Games?

A 5,000x bet is a decent payout for a slot. It isn't the highest, and there are bigger wins to be found, but it's still a jackpot worthy of a player's attention. If you're looking for a high RTP slot with a higher maximum win, we suggest Scientific Games' Gold Fish.

When compared to other Relax Gaming slots, Book of 99's jackpot payment ranks as average. However, two popular slots from the developer — Wild Chapo (10,000x et) and Money Train 2 (50,000x bet) — both rank higher when it comes to maximum payouts.

Book Of 99 Slot Bonuses

Outside of the Wild Scatter symbol, the Free Spins round is the only bonus feature in Book of 99. Three scatters will trigger 10 spins, as is the convention, but there's an extra way to trigger it too. Every time a Wild Scatter symbol lands on the reels it will be collected and added to a counter at the side of the screen. When that counter hits 99, the Free Spins feature is triggered. This function suits players who are going to be spinning the reels for a while.

Once triggered, a symbol will be selected at random. This symbol becomes the special Expanding Symbol for the duration of the feature, filling the reels to create winning combinations. This can be particularly profitable if one of the higher value symbols is selected, as two or more of this type constitutes a win.

Three more symbols will retrigger the feature, and there is no limit to how many times that happens.

Book Of 99 Bonuses
Book Of 99 Bonuses

Free Book Of 99 Online

Free slots are a great way to get to grips with the gameplay and features without risking any real money. Playing the Book of 99 demo version right here will help you get used to this slot and other titles with similar gameplay features.

In addition, Book of 99 is simply an enjoyable game to play. It's attractive and has a great soundtrack, so you may just want to play it for fun, and the freeplay version gives you that freedom.

Play Book Of 99 on Android or Apple

Relax Gaming is famous amongst players for its mobile slots, and Book of 99 does not disappoint in that regard.

The bold, yet simple graphics translate great onto smaller screens. The user interface has been adapted from the desktop version to ensure easy navigation and smooth playability for smartphone and tablet gamers.

Whether playing at your favourite mobile-friendly casino using your device's web browser or through a downloadable app for Android or Apple devices, you can enjoy seamless, lag-free gaming anywhere.

The Free Spins feature, minimum and maximum betting limits, expanding symbols, and Scatter Wild symbols of the desktop version are present on Book of 99 mobile, which also boasts the same jackpot of £500,000.

If you're looking for an enjoyable mobile casino experience that doesn't lose any of its quality on a small smartphone screen, Book of 99 is an excellent choice.

Book Of 99 Mobile

Similar Slots to Play Online

Greek mythology is one of the most popular concepts for online slots and has been for a long time. As a result, every top-named developer has turned their hand to this theme, which leaves players spoilt for choice when it comes to choosing a favourite.

Megaways, progressive jackpots, various paylines, jackpots, and bet limits - whatever you're looking for, there's a top-quality Greek mythology-themed slot that offers it. While Book of 99 is an excellent option, it would be remiss of us to not mention at least a few from the impressive array of other similar titles.

Divine Fortune
Divine Fortune

NetEnt, 96.59%

300 Shields
300 Shields

NextGen, 95.3%

Zeus 3
Zeus 3

WMS, 96.1%

Hot as Hades
Hot as Hades

Microgaming, 96.75%

Book Of 99 Online Review

On the surface, there isn't much unique about the Book of 99 slot. We've seen so many Greek mythology-themed slots that some players have lost interest in the concept. Plus, it has an Expanding Symbol in the Free Spins feature, like Book of Ra, Book of Dead, Book of Champions, and many more.

However, the ways that Book of 99 does stand out make all the difference. Firstly, of course, you have to consider the RTP. This is the big selling point of this Relax Gaming slot, and it has good reason to be. 99% is a rare and sought-after return-to-player percentage, putting Book of 99 above most other slots available at online casinos.

Players enticed by the RTP should also pay attention to the volatility. While the slot pays out well, it doesn't tend to do so regularly. It is important to remain aware that while big wins are promised by the low house edge, you may be waiting a long time before that happens.

Also worthy of note are the graphics of Book of 99. While similar to those of the slots mentioned above, they are produced with the trademark crispness that sets Relax Gaming apart. The images and animations pop off the screen and create a sense of immersion other Ancient Greece slots can't.

For Book of 99, we give this game a rating of 8/10. To learn more about our assessment and grading of casinos and games, check out our How We Rate page. We work closely with the independent regulatory bodies below to ensure every player on our site has a secure and reliable experience.

Gambling Commissiom
Gamcare Certified
McAfee
eCOGRA
GambleAware
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  • Game Theme and Symbols
    7/10
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    8/10
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Book Of 99 Reviews by Players

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9.4 / 10
Our Rating
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