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Book of 99 Slot Relax Gaming

Book of 99 Review - Editor’s Impressions

Enter the celestial ground and spectate the legendary fight of powerful Gods! The Book of 99 slot offers an unforgettable experience and a magical adventure. You can go on a journey where you can collect 99 magic books, and the Gods might stop to reward you with some great payouts. Read this Book of 99 slot review and prepare for what’s coming!

The Book of 99 slot machine is one of the games in our online slots reviews that use a fantasy theme but offer something distinctive. What we love the most about the game is how it offers two ways to activate the Free Spins. The visual aspect is impressive, there are two Free Spins features, and you can win up to 5,000x on a single spin. 

Overview of Book of 99 Game

The Book of 99 game isn’t the only fantasy-themed slot by Relax Gaming. However, you might be impressed that the slot is one of the most creative fantasy-themed slots we’ve encountered. The layout is a standard 5x3 with 10 paylines. 

You’ll spot a curving metre beside the reels and a number at the end of the line. The number starts at 99, and it’ll keep counting lower every time the magical book Wild lands on your reels. After the metre turns zero, you’re in for a surprise. 

You’ll meet some of the most powerful Greek mythology-based characters. The book we’re discussing has golden covers with two shining red stones on the front. It is the primary trigger to the Free Spins and works as Wilds that can help you create winning combinations. 

You’ll spot playing card symbols that pay less than the others. They only pay 0.5x to 15x, and you’ll get the payout from three to five of a kind on your grid. The four Gods will be the ones that reward you highly, giving 0.50x to 500x. Unlike the card symbols, the Gods pay from two matches. 

Book of 99 RTP, Payout and Volatility

Faithful to its name, the Book of 99 RTP is 99% with high volatility. You can wager £0.10 to £100 per spin and the max win is 5,000x the stake. 

Book of 99 Graphics and Gaming Experience

The Book of 99 slot machine will greet you with a movie-like cutscene showing a closeup shot of the golden book. The high-definition graphics clearly show all the details, and we were impressed by the visual details. 

In Book of 99 you’ll hear low-volume battle music, thumping and racing as you spin the reels. They’re not too upbeat but enough to amplify the excitement of going through the journey. 

Book of 99 Bonus Features

The Book of 99 slot does have a Wild symbol that substitutes for all other symbols except the special expanding symbols, but there are not any other bonus features. However, you’ll get two ways of receiving the Free Spins, and here’s how you can win them. 

Book of 99 Free Spins

As mentioned above, the book symbol acts as a Wild but has more purposes. You'll receive 10 Free Spins when three or more land on the reels. When you enter the feature this way, symbols can expand. They can cover up to 10 slot paylines so that you can receive the maximum payout. As long as they’re on a payline, they’ll give you a payout according to their values. 

The second way to activate the Free Spins is to use the metre on the left side. For every Wild that lands on the base game, the metre will collect it. The 99 counter will go down with each book, and the Free Spins game will start when it reaches zero. 

What separates the first and the second Free Spins is your bet amount. When you enter the Free Spins game by collecting the books, the slot counts the average bet you’ve placed throughout your gameplay. Therefore, instead of playing the free game using the stake that you have active when starting the feature, you’ll receive another number that can be bigger or smaller.

The features aren’t complicated or hard to understand, but if you want to take a peek, try the Book of 99 slot demo on our site. 

What Are the Pros and Cons of Playing Book of 99?

The Book of 99 game offers a lot of intense battles and journeys for players. However, the game still has flaws that players might not like. Here’s our Book of 99 slot review pros and cons list. 


  • Very high RTP
  • Free Spins come with expanding symbols
  • Wide bet range 
  • Impressive graphics


  • No other bonus features besides Free Spins

Where to Play Book of 99 Online

If you’re searching for a good Book of 99 online casino, check out our Relax Gaming online casino list. You’ll find our overview and other players’ reviews for each platform and then you can make a more informed choice. 

Not only do these casinos feature the Book of 99 real money, but they also feature other Relax Gaming games. You should check out Titan Strike, which has a similar theme from the same developer.

One of our top Book of 99 online casino recommendations is Oxi Casino.  

Summary of Book of 99 - 99% RTP and 99 Books to Collect

The Book of 99 slot machine intrigued us at first glance. The gameplay is straightforward, with only Free Spins and a theme many online slots had used. We were disappointed we didn’t see other features besides the Free Spins, but the book collection got us hooked. 

Book of 99 has amazing graphics and the cutscene opening of the game will catch your attention and make you question the role of the book. If you’re a fan of real money slots that don’t have too many complicated features yet still have a distinctive flair, Book of 99 may be just what you are looking for. 

Check out the Book of 99 slot demo above to get to know the game before playing for real money at UK online casinos.

Play game
Software Relax Gaming
Slot Type Video slots
RTP 99%
Special feature Wild Free Spins
top10 Slot details
top10 More slot details More details
  • Software
    Relax Gaming
  • Slot Type
  • Paylines
  • Reels
  • Min Coins Size
  • Max Coins Size
  • Jackpot

  • RTP
  • Bonus Game
  • Progressive
  • Wild Symbol
  • Scatter Symbol
  • Autoplay Option
  • Multiplier
  • Free Spins
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Book of 99 Slot Reviews by Players


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blondie 1632 reviews
Reviewed on August 23, 2021


Book of 99 is a slot from Relax game provider that was released earlier this year. To be frank, before it was released, I wasn't particularly interested in this game, because I thought to myself- how many book games can there be? And how can you create something new? Because for me it feels like there's so many book slots out there that it's difficult to come up with something new. However, when I read a few game reviews, I got more interested.

When it comes to the technical aspects of this game, it has 5 reels and 10 paylines and the minimum bet is 10 cents. I've played it a few times now and I play it with the minimum stakes or 20 cents. The slot is inspired by a fantasy theme and the main characters are several creatures, which definitely is an interesting twist for a book slot. Additionally, one of the first things that makes this slot stand out is the number 99, which plays a major role in this slot.

For one, the slot has 99% RTP and the game doesn't have a variable RTP. So casinos can only release it with this RTP and it took me a moment until I found a casino where I can play this game. And the second thing is the collection feature- whenever you get 1 book symbol, which is also the scatter, it will add the book to the collection meter. And when you've collected 99 books, you automatically get the free spins bonus. I think it's a nice added feature, as you can also trigger free spins by regular 3 book symbols. Also I like the fact that scatters are also wilds so you can get a good hit when entering the bonus round. With that being said, the free spins are your regular free spins with one special expanding symbol. I've had a few 200x bet wins so far, when I've had a premium symbol as my special symbol. But aside from that, I usually get around 40x-70x bet wins, nothing too special or significant.

Overall I do like this game and mainly because of the collection feature, as that makes it stand out from the rest of the book slots. Also the game design is very good and the color scheme is nice. The one thing I would have wanted to see is an elevated bonus feature when you've collected 99 books- it would have been nice that you get either 2 special symbols or more free spins. Other than that, it's probably one of the better book slots out there.
Fiekie247 1106 reviews
South Africa
Reviewed on May 31, 2021


Book of 99 – Aaah the slot game by Relax Gaming with 99% RTP – I wonder what that looks like, does it mean, I will basically always walk away with a positive balance or lose a maximum of a tenth of what I wager on the slot? Not sure, but I will find out in the future, provided I have not had a long session on this slot.

In the book of slots, everyone knows the drills when you play this slot, however, all of these slots just have a different theme. This slot reminds me of the Myth slot from Play'n Go. This slot has an ancient Greek theme with mythological characters like cyclopes, daemons, and male and female characters. The male who seems to be the hero is like Rich Wilde and the most rewarding symbol in this case. Getting a full screen of the hero will award you with x5000 your total bet. That means a 5OAK on 1 pay line will reward you with x500 your total bet.

The book has a substitute for all symbols and serves as a scatter as well. Landing 3 or more books triggers the free spins feature with an expanding symbol. If you managed to get 5 books anywhere on the reels, you will be getting x200 your total bet scatter win and more to the point if the 5 books are connecting on a pay line an additional x500 win will be rewarded as well.

During free spins, a special expanding symbol is selected and serves as a scatter. Landing 3 or more of them anywhere on the reels will give wins according to the paytable for the lower value symbols. High-paying symbols just need 2 of a kind during free spins for a win.

You can either trigger the free spins naturally with 3 books or you can play for a while and collect book scatters 99 of them to be exact which usually takes on average between 300 – 400 free spins to reach and the free spins will be awarded as well.

The max win on this slot is x5000 your total bet and the feature ends.
Sloter 514 reviews
Reviewed on May 12, 2021


Psalm 69 or Book of 99?
Probably, Book of 99.

The 'Book of 99' is a 5 Reel/10 Payline 'Book Of' video slot developed, by Relax Gaming with an RTP of 99% rate which overcomes the standard barrier of 96% rate. (At least that's what the developer states). However, according on my 2 sessions/deposits of 10 Euros each, by betting on lowest 10c/per spin on 1 Casino brand, I noticed something completely different.

But, first thing first the positives:

The provider mixes some famous myths of Ancient Greek mythology, which extend throughout the Mediterranean Sea, such as: Odysseus/The Cave of Kirki/Island of Calypso/Port of Laistrigona/Cave of Polyphemus. The visuals/sounds and Paytable standing on decent level - as the most of Book Slots in Gaming industry while the The Book symbol represents the Scatter/Wild. Also the slot offers 3 Ways triggering the Free Spins feature.

The first is the classic where, Players need to land 3 or more Scatter/Wild symbols to activate 10 Free Spins, with a special Expanding symbol for the whole of the feature.

The second way entering, is by the Collection feature. With each time a Wild symbol lands, Players will progress, along an Ancient Greek map/meter to the left of the reels. When the meter reach 99 Wilds, the Free spins are triggered.

The third way, is when Simultaneously landing 3 or more Wild symbols and completing the collection in the same spin, first the Wild triggered Free Spins are played, followed by the collection triggered Free Spins.


Now the negatives:

1. Inside slot information, does not state how much the Wild Book it pays as a Symbol, while on many gambling sites, are stated that it pays up to 500x bet for 5 of them (?)

2. In my opinion, the triggering map feature can be very deceiving, while it cost me 2 deposits of 10 each, to activate the feature, with small amount in return. The thing is that i'm not complaint here about the amount in return, but for the whole behavior of the mechanism.

For those who play 'Book Of Slots' they need the teaser mechanism, to improve the landing. In this slot i've never encounter a tease, on my 2 sessions, only 1 or 2 Book Wilds, to be added to the meter collection. Also, noticed only 3 Of-a-kind wins with rare 4 Of-a-kind. Never 5 Of-a-kind, not even with '10' Symbol.

3. The slot's simulated max win, extends to 12.000x bet. Summing up my conclusion, better to risk my money, on 'Spearhead's - Blue Diamond Book' with potential up to 27.000x bet/Plenty of teasers and re-triggers, because simply I need a Book to land, not a fancy Theoritical RTP.

In overall, don't judge a book by its cover, sure... However, judge a book slot by, how it performs!

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