Book of 99

Editor's rating:
Published: April 20, 2021|Updated: April 21, 2021

Book of 99 Slot Review (Relax Gaming)

Book of 99 is a slot with 99% RTP from Relax Gaming.

Not only that but as the name implies, it’s based on the popular “book” slot concept (Book of Ra, Book of Dead, etc.). This of course includes the free spins bonus with a special expanding symbol. This time, however, it can also be triggered through a bonus collection feature that will keep track of your average bet as well. And instead of the Egyptian theme, the Book of 99 is designed around Greek mythology, helping it stand out a tiny bit more from a plethora of similar games.

Book of 99 is available at Relax Gaming slot sites like Rizk from 4 May 2021.

Play Book of 99 at Licensed Slot Site
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99% RTP

Book of 99 has a theoretical average return to player of 99%. Such high RTPs are usually seen in table games but not slots, with a few exceptions like NetEnt’s Mega Joker (99%) or Thunderkick’s 1429 Uncharted Seas (98.5%)

The RTP in itself is not a perfect indicator of short-term wins or losses. In the long term, this translates into lower margins or house advantage for the operator/casino, by as much as four times when compared to slots with an average of 96% RTP. Theoretically, this should mean quite a bit in savings and extended gameplay for the players, but as we know human is not always rational, and far from that when choosing to play slots. This slot would be the most rational within the context.

Single-line wins can pay up to 500x with the best symbols.

Base Game

Book of 99 has 5 reels and 10 fixed lines. Symbols are also easy to track. There are 10 different icons that come non-stacked and that pay up to 500x for a single full line. The book symbol is both Wild and Scatter.

The hit frequency of 29.83%, which is relatively high to the 20% baseline in high variance slots.

👍 Tip: Some casinos limit bonus wagering on high-RTP slots, so Book of 99 will be the first one to be excluded if this is the case.

Free Spins with Special Expanding Symbol

Special expanding symbols pay in scattered positions too.

One way of winning 10 free spins is by getting 3 or more of the special Scatters/Wilds. Unlimited re-triggers are also possible the same way.

Once triggered, the bonus will shuffle from a deck of existing symbols to pick a special expanding symbol that will expand and pay scattered, according to the paytable. Getting the high symbol is obviously the best but it’s just as difficult to trigger any bonus wins with it.

The average win in the bonus is 68.8x, which is good considering the fact that you’ll get the free spins one or the other way within 15-minutes of play on average. Based on my experience, however, it is very rare when wins break the 200x barrier.

Bonus Collection

Only 1 special symbol is needed to make it expand on that reel.

The other way to win the bonus is by getting 99 Wilds/Scatters.

For every Wild symbol, the collection meter will move +1 and keep track of the bet amount that triggered it. Get to 99 to trigger the bonus spins, which will be played at the average bet. Here are some more useful stats:

  • Big Win probability (15x bet or more) – 1 in 108
  • Mega Win probability (30x bet or more) – 1 in 180
  • Epic Win probability (60x bet or more) – 1 in 305

For comparison, the probability of an Epic Win in Money Train 2 is 1 in 418.

👍 Tip: The average win in the bonus is 68.8x.



Editor's rating:

It seems that the high RTP comes at the expense of very linear gameplay. Even though Book of 99 is played at high volatility, you can go for thousands of spins without deviating much from where you started with your balance. One way the more risk-prone players can add risk is with higher bets, which this slot accommodates very well having a flexible betting range of between 0.10 and 100 credits per spin. The high RTP provides quite a bit of safety, but it doesn’t make for the most interesting of slot sessions as bets above 200x are reserved for the best days. That is until against all odds you get one of the high symbols expanding during the free spins, which Relax Gaming claims to have simulated wins of over 12,000x bet.

While Book of 99 certainly has an interesting concept to complement the famous series, players expecting anything more than the good old “book” concept may be better off with Play’n GO another Book of Dead sequel called Rich Wilde and the Amulet of Dead, which just became available. For those of you who are concerned about Book of Dead’s RTP being lowered to 94% at some slot sites, Book of 99 with its fixed 99% RTP will be an interesting find.

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No wagering requirements on this signup bonus. Rewards must be claimed within 7 days. No code needed. New 18+ customers only. Play responsibly. Full T&C apply.

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