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Book of 99™ slot by Relax Gaming

Book of 99™
Book of 99™
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Updated: 22.07.2025
Reviewed by: Joe Booth

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In this review
  1. Slot details
  2. Theme
  3. Book of 99™ Bonus Features
  4. Summary
  5. Where to play
General information about Book of 99™ slot

General information about Book of 99™ slot

Rating by Joe Booth:
9.8
Relax Gaming
Write a review +25 SJ points
  • Release Date:
    04.05.2021
  • Volatility:
    High
  • RTP:
    99.0%
  • Multiplier:
    No
  • Max. win:
    5,000x
  • Bonus game:
    No
  • Free spins:
    Yes
  • Scatter Symbol:
    Yes
  • Wild symbol:
    Yes
  • Symbol Stacked:
    No
  • Jackpot Game:
    No
  • Slot lines:
    10
  • Slot reels:
    5
  • Layout:
    5-3
  • Stakes range (€/£/$):
    0.1 to 100
  • Slot Theme:
    Ancient civilizations
  • Technology:
    JS, HTML5
More infoLess info

Licensed and tested by

  • AGCO
  • eCogra
  • Gambling Comission
  • HM Goverment of Gibraltar
  • MGA
  • ONJN

To stand out in the crowded world of slot machines, developers need to be creative. For example, choose an unusual theme or come up with innovative bonus features that no one else has seen before. The Relax Gaming developer followed a learned scenario. As you can tell from the name, Book of 99 is another "Book" slot machine.

This time the action takes place in Ancient Greece. The playing field, consisting of 5 reels in 3 rows, gives 10 paylines, using which you can reach the maximum win of 5,000x your bet. The betting range here is from 0.10 to 100 coins and bonus features include Free Spins, Wilds, Scatter, and Expanding symbols.

RTP & Volatility

An interesting step on the part of the provider was the addition of an attractive RTP value of 99%, which refers to the name of the slot, as well as the addition of a generous collection system. The volatility is high, so you have the opportunity to compete for a big prize.

Gameplay

8.8 
Gameplay

Mobile compatibility

Mobile compatibility

Book of 99™ Bonus Features

9.8 

Game Symbols

In this Greek odyssey, you will find a group of unpaid symbols: Ace and King pay up to 15x if you land five, whereas Queen, Jack, and Ten pay up to 10x, Jack pay up to 10x your bet.

The higher-paying characters are the Baby Eater Monster Lamia – up to 75x your bet, Cyclops – up to 75x too, as well as female protagonists up to 20x and male protagonists up to 50x. The book is a special Wild symbol that pays nothing, rather substitutes for all symbols except the special expanding symbol in Free Spins.

Book of 99 online slot - big win

Bonus Rounds & Free Spins

Free Spins Feature

As always, you need the Book to activate the best moments of the gameplay. Not only is this Wild, a substitute symbol for completing prize combinations, but Scatter – 3 or more gives you a round of 10 free spins, but without additional payments, which is a little unusual. Before the start of the bonus round, one of the standard symbols is randomly selected as an Expanding symbol for the duration of the feature.

Finally, let's take a look at the next feature, the Wild Symbol collection system. For each Wild symbol landed in the base game, the scale near the playing field is increased by 1 time. Filling the counter with 99 collected Wilds will earn you a round of 10 free spins. The launch takes place according to the same rules, so Expanding symbols come into the feature.

Book of 99 online slot - free spins

Overall Rating

9.8

The appearance of the slot is great for such a theme, and the bonuses are quite good. We would like to say about the main advantage – RTP. We opened our eyes wide when we saw such large numbers. Well, the provider is countering the downward trend by blessing a new slot machine with 99% RTP. Call it what you want – a tricky move or a gimmick to attract players, but at the end of the day, it's a feature that makes Book 99™ more desirable than many “Book” slots.

Hits
Very high RTP of 99%
Collecting Wild Symbols feature
Free spins round
Misses
High volatility
A hackneyed theme

FAQ

What is the maximum win I can get?

In this new slot machine, the maximum theoretical win is as much as 5,000x the stake!

Can I get the Free Spins feature?

Three or more Book symbols give you a round of 10 free spins. Also, for each Wild symbol landed in the base game, the scale near the playing field is increased by 1 time. Filling the counter with 99 collected Wilds will earn you a round of 10 free spins.

Can I play in the Demo version?

Yes, you can get acquainted with the slot machine for free by launching it in the Demo version.

Does the slot have a progressive jackpot?

No, there is no progressive jackpot in this release from Relax Gaming, but you can compete for it in other slots from the same company.

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Joe Booth
Joe Booth
Expert in: News, Blog, Slot reviews, Payments
Joe is an expert online casino player, who knows all the tricks and tips on how to get to the most massive wins. He is also an experienced online casino games reviewer, with hundreds of written articles behind him, on all kinds of online casino games. He makes sure to play them, see how they work, and then gives his honest expert opinion about them to other players, our readers. 

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