Book of 99

|Relax Gaming|2021-05-04|RTP: 99 %
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Game provider
Relax Gaming
Book of 99
Feature Buy
Game type
Video Slots
Mobile version
Grid slot
Sticky wilds
Free spins
Bonus game
Very high
Progressive jackpot
Min. bet
Random Feature
Max. bet
Maximum win
Last update
May 3, 2021


4 votes - 4.25/5.00

Join two fearless warriors as they embark on a fantasy reel adventure on the slot from Relax Gaming. Thanks to its exceptional RTP of 99%, Book of 99 is not just another addition to the sheer endless number of games with the special expanding symbol mechanic in the bonus feature. Nevertheless, it is still volatile and can deliver wins of up to 12,075 times your bet while also having a special twist to trigger the free spins.

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Slot Details

Book of 99 is a video slot with five reels, three rows and 10 fixed pay lines. Wins are awarded for two to five matching symbols landing on a line from left to right only. Available for play on desktop, tablet or mobile from 0.10 to 100 credits per spin. The game has high volatility with an exceptional RTP of 99%.

A fantasy nature scene is in the background of a the game window filled with weird creatures, brave warriors and naturally books. Held in a solid stone frame, it resembles the entry to a palace or temple. Worth keeping an eye on is the meter to the left of the reels as it is the second option to trigger the main event. A mysterious soundtrack provides the main audio.

Book of 99 Screenshot

The pay symbols start at the low end with the usual card royals from 10 through to A, awarding 10x to 15x your stake for a single five of a kind. The premiums are cat woman, ogre as well as a female and a male warrior. Hit five on a line to win 75x to 500x your bet. The fabled book ornamented with a 99 serves as the wild and scatter symbol. It will substitute for any other symbol.

Book of 99 Slot Features

Slot connoisseurs and “Book of…” fans will most probably know what to expect when it comes to bonus features since most will have given at least Book of Dead a few spins. After all, there are meanwhile 100s of games populating online casinos lobbies that have the expanding special symbol mechanic at its core. However, Relax Gaming is taking us into unknown territory with the high RTP while the secondary feature trigger further separates it from the rest of the crowd.

Book of 99 Free Spins

The game has two ways to trigger 10 Free Spins. Either hit three or more Book scatters anywhere on the reels in one spin or collect 99 scatters which are added to the meter on the left of the game window (desktop). Any time one or two scatters land, they will be accumulated and trigger the free spins when the meter is filled. Contrary to other “Book of …” slots, there are no coin wins for three or more scatters.

The organic feature will be played at the bet size from the triggering spin while the one awarded through the collection will be played at the average bet size of the base game spins that contained one or two scatters. For both, there are unlimited retriggers available by landing three or more scatters during the feature.

Before the start, the game will randomly select one of the nine pay symbols to be designated as the special symbol for the round. When sufficient land on a free spin, they will expand vertically to cover the entire reel and award wins for all pay lines, even when they are not adjacent or on a line. It will need a minimum of three low-paying symbols or minimum two premium symbols anywhere on the screen to see them expand and award a win, which will be paid on top of any potential line wins. The feature ends when you run out of spins.

Final Verdict

Game providers daring enough to release a slot with an RTP of 99% should be commended and nominated for all kinds of awards. While Book of 99 does the same as all other “Book of…” slots, it will stand out from the crowd by a mile for its RTP value alone. Plus, it has the extra feature trigger to further separate itself from the others. Surprisingly, my hours of testing showed that it can be still very volatile which is a must for “Book of…” slots. High risk, potentially high rewards as they say.

Book of 99 – Frequently Asked Questions (FAQ)

1. Is the RTP on Book of 99 indeed at 99%?
2. What is the maximum win potential on Book of 99?
3. Can I play Book of 99 with bonus funds?


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