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Book of 99 slot

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When you hear the words “book of”, what is the first thing that comes to mind? It could be nostalgia or perhaps even boredom because there are more than a few book slots in the industry. Nonetheless, Relax Gaming woke up one morning and decided to make another one, but there is a catch. Book of 99 is special because it is a slot that comes with an RTP of 99%. This is much higher than the average rating, which usually is around 96%. Is this just a gimmicky selling point, or does the 99% actually makes a huge difference? We will have to see as we go.

You need to be innovative to be successful, this is something that we’ve always been preaching. There are many ways to be unique and this supposedly is one of them. We don’t ever recall seeing such an RTP before, so Book of 99 is doing something differently, that’s sure. But is this going to be enough to attract a large player base? Perhaps only time will tell, but we will try to come to our conclusion. Using Ancient Greece as the setting, the Book of 99 also brings forth a familiar feeling.

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Book of 99 Slot Review

Relax Gaming
Provider: Relax Gaming
Game Layout
5 Reels x 3 Rows
Game Layout: 5 Reels x 3 Rows
Paylines: 10
Volatility: High
RTP: 99%
Max win
Max win: 12,075x
Bet Range
0.10 - 100
Bet Range: 0.10 - 100
Bonus features
yes (2) Free Spins, Wild Collection
Bonus features: yes (2) Free Spins, Wild Collection
Release date
4th of May 2021
Release date: 4th of May 2021

Gameplay and Payouts

Undoubtedly the most famous setting for a book slot is Ancient Egypt, but Ancient Greece also follows closely behind. Book of 99 visits the mythological side of the culture, focusing on some of the creatures and legends. It’s quite a simple-looking book slot, definitely more simple than some other recent slots we’ve seen from Relax Gaming. Book slots usually come with more plain presentations, so we can’t bash Relax Gaming too much. There is a strange, almost eerie like feel to the Book of 99 slot. Perhaps it’s due to some of the symbols or because of the abrupt silence that follows after you pause your spins.
book of 99 symbol
Book of 99 is a 5 reel slot with 10 paylines, so we do closely follow the standard set up. The symbols of the game aren’t all that impressive, but a few of them do set an interesting tone, as we mentioned before. Low symbols are 10 – A made from stone and styled with colourful gemstones. High symbols are some characters, such as Minotaur and Lamia. The wild symbol is a book with two 9’s on it, shaped like lightning bolts. You read that correctly, the book is the wild not the scatter, which is not even present on the Book of 99 slot.

Book of 99 is all about that 99% RTP. That is the main selling point and that possibly is the best stat of the game. To be fair, the 12,075x max payout is also very attractive, but it’s slightly overshadowed by the return rate. Unsurprisingly, Book of 99 is a high volatility slot. The bet range also is very textbook, being 0.10 – 100. These are elementary book of payout stats, but they do manage to stand out from the general bunch. Book of 99 can be tried out on all devices, which surely is great news for mobile gamers.

Bonus Features

The Main Book of 99 bonus feature is Free Spins. There are 2 ways to trigger the bonus, the classic approach and the more unique option, which Relax Gaming have added. The usual way is to get 3 or more books, which then awards 10 Free Spins. The other way is to collect 99 wild symbols/books during the main game. There is a collection meter on the left side that will keep track of the collected books. The Free Spins bet will be determined by the average bet value during the collection phase.

book of 99 free spins

Once Book of 99 Free Spins are triggered by one of the ways, a special Expanding symbol will be selected. This is just like we’ve seen on all the other book games, such as Book of Dead. Once the special symbol lands during Free Spins, it expands fully to cover the whole reel. Symbols don’t need to be connected for a payout to occur. Landing 3 additional wilds will retrigger the feature.


It’s a new and interesting idea by Relax Gaming to add the 99% RTP to Book of 99. If it weren’t for this, the Book of 99 slot would be another basic book of game, which would most likely fade away within time. Casual players won’t really notice a huge difference the 3% makes, but in the long run, it can give you a slight advantage. We also appreciate how Relax Gaming added two separate ways to trigger the bonus. If you are struggling to hit 3 books at once, at least you have a guaranteed chance to trigger the bonus once you reach that special 99. Overall, it’s a positive release by Relax Gaming. We can appreciate the effort to create something new and special. Book of 99 Is just that, so we believe it’s worthwhile to check it out.


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