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Book of 99 (Relax Gaming) – Review & Demo Play
Book of 99 from Relax Gaming play free demo version ▶ Casino Slot Review Book of 99 ✔ Return (RTP) of online slots on July 2026 and play for real money✔
- Substantially revised the review with updated stats, a detailed look at the Book Collection Meter, and added pros and cons.
Pros
- Rare 99% RTP, the highest in the genre
- Book Collection Meter guarantees a bonus path
- Expanding symbols pay Scatter style
- Free spins retrigger with no limits
- Simple 5x3 grid, easy to read
Cons
- Very high volatility punishes short sessions
- Modest 29.83% hit frequency, long dry spells
- Collection meter drags when Books stop landing
- No Bonus Buy on most sites
First look at Book of 99
Book of 99 is Relax Gaming's book slot built around a 99% RTP, the number that gives the game its name. Ancient Greek mythology sets the scene, with warriors and gods on a 5x3 grid over 10 fixed paylines. The hook is the Book Collection Meter: collect 99 Book wilds and the bonus fires. Straight up, that RTP is the pitch.
I run this on high stakes and the number reads honest around 99%, not marketing fluff. First spins feel calm, low chaos, standard book layout. The swing hides behind that friendly return, so do not be fooled. It hits or it doesn't, and the meter is what keeps me spinning.
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RTP and volatility behaviour
99% RTP is the highest you will meet in the book category, well above the 96% average most slots settle at. That extra return buys you more spins per bankroll, plain maths. But high stakes expose the variance fast, and the 29.83% hit frequency means roughly one win every 3.35 spins. The swing is brutal, own it.
Max win sits at 12,075x, respectable but short of the 50,000x monsters out there. The average free spins payout lands near 68.8x total bet, which tells you the big screens are rare. Bankroll's gone before the feature lands if you rush it. Either it pays or it burns, no reason to sugarcoat it.
Reading the paytable
Apollo runs the top of the ladder, paying 500x for five on a line and a full 5,000x for a complete screen. Behind him sit Pythia at 200x, then Lamia and Cyclopes at 75x for five. Royals A and K pay up to 15x, while Q, J and 10 top out at 10x. Clean hierarchy.
The Book Wild/Scatter does the heavy lifting. It substitutes for every symbol except itself and triggers the free spins on 3 or more. High-value symbols only need two to start paying, which pushes those bigger line hits. The Greek art is sharp, though the night-time soundtrack loops the same battle motif and wears thin after a few minutes of grinding.
Symbols and payouts
| 5 | x500 |
| 4 | x100 |
| 3 | x10 |
| 2 | x1 |
| 5 | x200 |
| 4 | x40 |
| 3 | x4 |
| 2 | x0.5 |
| 5 | x75 |
| 4 | x10 |
| 3 | x3 |
| 2 | x0.5 |
| 5 | x75 |
| 4 | x10 |
| 3 | x3 |
| 2 | x0.5 |
| 5 | x15 |
| 4 | x4 |
| 3 | x0.5 |
| 5 | x15 |
| 4 | x4 |
| 3 | x0.5 |
| 5 | x10 |
| 4 | x2.5 |
| 3 | x0.5 |
| 5 | x10 |
| 4 | x2.5 |
| 3 | x0.5 |
| 5 | x10 |
| 4 | x2.5 |
| 3 | x0.5 |
How the bonuses trigger
Two paths lead to the bonus. The standard route needs 3 or more Book scatters anywhere for 10 free spins. The second is the collection meter: bank 99 Book wilds across the base game and 10 free spins drop automatically. That guaranteed path is the real difference from a plain book slot, no debate here.
Inside the feature, one symbol is picked at random to expand. Character symbols need just 2 anywhere to fill their reel; royals demand 3, which is the weaker draw. Expanded symbols pay Scatter style, no need to line up across paylines. Land Apollo as the expander and 5,000x per spin comes into range.
Retriggers stay live with no cap. Three or more Books during the spins add another 10, and stacking those is how you reach the 12,075x ceiling. The frustration is real when the meter stalls at 80-something Books and the wilds just stop landing. That final stretch to 99 can feel dead.
Bonus features
FAQ
How many Book wilds do you need to fill the collection meter?
Why do royal card symbols make the free spins weaker?
What is the average win during the free spins feature?
Can you retrigger the free spins, and how many times?
How does Book of 99 compare to other Relax Gaming book slots?
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Our editorial team
All our content is written by our editorial team and checked before publication. We play the games ourselves, verify licences and withdrawal terms, and update every review as soon as something changes.
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