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Book of 99 Slot Relax Gaming

Book of 99 Slot is powered by Relax Gaming with 5 reels, 3 rows and 10 fixed paylines. Relax Gaming has rewritten history with this game as you will battle amongst the gods on a first of its kind 99% RTP slot! The game has the potential to dish out some serious wins thanks to features that include Free Spins and a Collection Meter. You can try the Book of 99 Slot at AskGamblers for free or at any Relax Gaming Casino in real mode. 

How to Play Book of 99 Slot 

Before you can unleash your inner God you’ll need to learn how to place your bets:

  • Clicking the +/- values can increase and decrease your bet. This will form your total bet per spin
  • Hitting spin will set the reels in motion
  • If you get of spinning the reels you can use the Auto Play feature

Slot Features 

In terms of features the game is pretty straightforward and comes with an attractive Free Spins game with expanding symbols. There’s a Collection feature too which is a second way of triggering the Free Spins. 

Free Spins

There are two ways to trigger this feature but the main way is when you land at least three or more Wild Symbols on the same spin. This will automatically trigger 10 Free Spins and one standard symbol will be picked at random. This will then transform into an Expanding Symbol for the duration of the Free Spins. 

Whenever the chosen symbol appears it will expand to fill the entire reel, potentially producing some epic wins. This symbol can also pay out on all 10 paylines depending on how the symbol has landed on the reel. 

What’s so great about these symbols is that winning combinations don’t have to be connected. An example being expanding symbols that fall on reels 1, 3 and 5 will result in a winning combination being formed during Free Spins. The maximum win will depend on which symbol became the expanding symbol and can vary from 100x to 5000x. 

Landing a further 3 Wild symbols will also trigger another 10 Free Spins and there is no limit to the amount of retriggers you can collect. 

Collection Feature

The other way to trigger Free Spins is through the Collection Feature. There is a meter to the left of the reels and every time you land a Wild Symbol you will start filling this meter and progress through a treasure map. 

When you have filled the meter which takes 99 Wilds you will trigger Free Spins which will have the same expanding symbol feature we mentioned above. Once the 10 Free Spins have been played the meter will reset itself and you’ll start the quest all over again. 


The main focus of this latest game from Relax Gaming is it’s 99% RTP which is sure to attract a lot of attention. In fact, you’ll be pushed to find a game on the web that offers this kind of Return to Player percentage and is a very smart move from the leading software providers. 

The game has the potential to payout 5000x your total stake during Free Spins and this is all down to the Expanding Symbol feature. How much this feature pays out will entirely depend on which symbol is chosen at random at the start of the Free Spins. If the game selects one of the higher paying symbols you’re looking at a pretty decent multiplier. The game's simulated max win potential actually extends to 12075x your total bet. 

The fact the game also has two ways to trigger these Free Spins is another selling point and we believe that this game is definitely worth a shot. 

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 1592 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 1104 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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