Book of 99 slot review (Relax Gaming)


Book of 99: is the best paying slot of all time. Relax Gaming states on their website that they’re “rewriting history” with this slot. While that may be a bit of an understatement, this high-paying Book of Ra clone is making a lot of waves.

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Release Date:
May 2021
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Book of 99 has an RTP of 99%(!), and it’s indeed the best paying online slot of all times!

It’s (obviously) also the best-paying Relax Gaming slot, the best-paying Book of Ra slot, and it will take some time before someone will top that!

Okay, Netent’s Mega Joker matches this generous RTP, but you can only benefit from it if you play the maximum bet and play the top game.

Besides, the slot is ten years old, way too old, and too dull.

Book of 99 has much more to offer, besides the RTP, as it’s a joy to play. It’s not just an ordinary Book of Ra slot, as it has more options.

I’ll tell you all about it below!

Gameplay and Features

It’s a 5×3 slot with 10 fixed paylines.

The slot has an Ancient Greek theme, and Midas (the God of war) is indeed the highest-paying symbol. A five-of-a-kind gets you a 500x win.

The other highs are two female Godesses and a one-eyed cyclops. The lows are 10, J, Q, K, and A.

The Book of 99 symbols are the Wilds. You can trigger the free spins in two different ways.

Way 1: Trigger the Free spins by landing three wilds

If you manage to land three or more wild symbols, you gain ten spins.

Way 2: Trigger the Free spins by collecting 99 wilds

Another way is by collecting 99 wild symbols during the base game. On the left-hand side, you see the collection meter, which is filled, by one step, for each wild symbol you spin.

The free spins – a special expanding symbol

Now, you see the typical Book of Ra features. A special expanding symbol is randomly selected.

The special symbol expands over an entire reel if you make a win. It helps that the symbols do not necessarily have to be adjacent, starting from the first reel.

For example, if you have three identical symbols on reels 1, 3, and 4, that’s just as well a winning combination.

Indeed, if the special symbol is the highest paying symbol (Midas), you can land 5000x with one spin if you manage to land this symbol on all the reels.

The payout percentage (RTP) of Book of 99 is 99%

The RTP of the main game is 99%, and I guess we’re informed by now, loud and clear!

The variance (volatility) of Book of 99 is high

Book of 99 is a medium to high variance slot, and the max win is just over 12000x.  I expect to see more than enough wins exceeding 5.000x (a full screen of the best paying Midas symbols).

Book of 99 slot – Pros en Cons



  • I’m getting a bit repetitive, but indeed the RTP of 99%!
  • More than substantial win potential.
  • The max win is more than double than of Book of Dead’s max win.


  • We have seen too many Book of Ra slots.