Age of the Gods Slot
Book of 99 Slot Review
Relax Gaming
Take a trip back in time to meet Zeus and his friends, and enjoy an epic 99% RTP with Book of 99 by Relax Gaming.
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Enjoy a Mythical 99% RTP with Book of 99!
In an industry where 'Return to Player' percentages have been steadily trending downward, Relax Gaming flipped the script with the release of Book of 99. While it identifies as a classic 'Book of' style slot, it distinguishes itself with a staggering, market-leading 99% RTP - a figure almost unheard of in the modern era of online gaming.
Set against a backdrop of Ancient Greek mythology, Book of 99 isn't just a statistical anomaly - it's a high-production odyssey! Beyond the standard expanding symbol mechanics that fans of the genre crave, Relax Gaming has introduced a persistent Wild Collection system.
By collecting 99 wilds during base gameplay, you get guaranteed entry into the free spins round, ensuring that every spin contributes toward your goal. With a massive win potential of 12,075x your stake, it is a title that balances extreme mathematical value with the explosive volatility required for a truly 'epic' hit.
Quick Game Stats
We're going to tell you everything you need to know about this game shortly, but in the meantime, here are some of the most important Book of 99 game stats.
| Feature | Specification |
|---|---|
| Software Provider | Relax Gaming |
| Reel Layout | 5x3 |
| Paylines | 10 Fixed |
| RTP (Return to Player) | 99.00% |
| Volatility | Very High (5/5) |
| Maximum Win | 12,075x Total Stake |
| Betting Range | $0.10 – $100.00 |
| Main Features | Wild Collection Meter, Free Spins, Expanding Symbols |
| Hit Frequency | 29.83% |
Theme & Design
Visually, Book of 99 deviates from the dusty, sandy tombs of typical Egyptian 'Book' clones, opting instead for the sun-drenched, olive-rich landscapes of Ancient Greece. The design carries the distinct Relax Gaming touch - clean, sharp, and slightly stylized with a cartoonish edge that brings its mythological cast to life.
The 5x3 grid is set within a stone-carved temple, where players encounter a collection of beautifully rendered mythological figures. You’ll meet the child-eating daemon Lamia, a hulking Cyclops, the high priestess Pythia, and the God of Light, Apollo. The atmosphere is elevated by a harrowing, exotic soundtrack that sets a battle-ready tone as you approach the final books needed for the bonus trigger.
How to Play Book of 99
Getting started with this Greek odyssey is straightforward, as it follows the classic 10-payline structure that 'Book of' fans will find instantly familiar.
Adjust Your Stake: Use the 'Bet' selectors to set your wager. Most platforms offer a range from $0.10 to $100 per spin, ensuring both casual players and high-rollers can enjoy the 99% RTP.
The Goal: Match 3 to 5 low-value symbols (10-A) or just 2 to 5 high-value character symbols across any of the 10 fixed paylines from left to right.
The Wild/Scatter: The 'Book' symbol is the most important icon on the grid. It acts as a Wild, substituting for all other symbols to create wins, and also as a Scatter to trigger the Free Spins round.
Dual-Trigger System: Unique to this title, you don't just wait for 3 Scatters to land in a single spin. Every single Book symbol that lands is collected in the 99-Wild Meter on the left. Once you hit 99, you are guaranteed entry into the bonus.
Symbol Values
The paytable is generous, particularly with the character symbols. Even landing just two of the higher-tier icons will result in a return, while a full line of Apollo offers a massive base-game hit.
| Symbol | 2 Symbols | 3 Symbols | 5 Symbols (Max) |
|---|---|---|---|
| Apollo (Red) | 1x | 10x | 500x |
| Pythia (Blue) | 0.5x | 4x | 200x |
| Cyclops (Green) | 0.5x | 3x | 75x |
| Lamia (Purple) | 0.5x | 3x | 75x |
| A, K Royals | - | 0.5x | 15x |
| Q, J, 10 Royals | - | 0.5x | 10x |
Bonuses & Special Features
While the base game provides steady action thanks to that 99% RTP, the real power of Book of 99 lies in its free spins and the innovative collection mechanic.
Free Spins with Expanding Symbols
Landing 3 or more Book Wilds in a single spin triggers 10 free spins. Before the round begins, the book flips through its pages to randomly select one standard symbol to be the special expanding symbol.
The Expansion: During the bonus, if enough of the chosen symbol lands to create a win, they will expand to cover their entire reel.
Scatter Pays: These expanded symbols do not need to be on adjacent reels to pay out; they pay across all 10 lines from any position.
Retriggers: Landing 3 more Books during the round adds another 10 free spins to your total, with no limit on how many times this can happen.
The 99-Wild Collection Feature
This is the standout innovation from Relax Gaming. Every time a Book Wild lands in the base game, it fills the meter on the left side of the screen.
Guaranteed Bonus: Once you collect 99 Wilds, the Free Spins round is triggered automatically.
Fair Payouts: The bet level for these 'collected' free spins is determined by the average of the bets used to collect each of the 99 Wilds. This prevents players from 'gaming' the system by switching to high stakes only at the very end of the meter.
12,075x Win Potential
While a single screen of the top symbol (Apollo) pays out 5,000x, the total feature win cap is a massive 12,075x your stake. This is significantly higher than the standard 5,000x cap found in most 'Book of' clones, making Book of 99 a top-tier choice for those chasing a legendary hit.
Win Potential & Volatility
If the 99% RTP suggests a gentle ride, the volatility levels of Book of 99 say otherwise. Relax Gaming has assigned this title a 5/5 variance rating, meaning it is built for the high-risk, high-reward 'swing' style of play favored by veteran slot fans.
Maximum Win: While a single-screen payout (filling the grid with Apollo) is 5,000x, the calculated maximum win potential for a full feature sequence is an impressive 12,075x your stake. This is a significant jump from the 5,000x cap found in the industry's most famous 'Book' games.
The 99% RTP Factor: It is important to understand what a 99% RTP means in a high-volatility setting. It doesn't guarantee frequent small wins; instead, it means the house edge is a razor-thin 1%. Mathematically, more of the money wagered is returned to the player base over time, but those returns are concentrated in the massive 12,075x spikes rather than distributed in small drips.
Hit Frequency: The game boasts a hit frequency of 29.83% (approx. 1 in 3.35 spins). This keeps the base game feeling active while you work toward the 99-Wild collection goal.
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Mobile Experience
Relax Gaming is renowned for its sleek, high-performance software, and Book of 99 is a testament to their mobile-first philosophy. Built using HTML5 technology, the game is fully optimized for this generation of smartphones and tablets.
Pros & Cons of Book of 99
Massive 99% RTP
12,075x max win
Guaranteed bonus
Saturated theme
Base game a little slow
Final Verdict
In the saturated world of 'Book of' slots, Book of 99 is a rare statistical marvel. While most developers in 2026 are tightening their margins, Relax Gaming has delivered a gift to the player community. By combining an industry-high 99% RTP with a significantly boosted 12,075x max win, they have created a game that isn't just a copycat - it’s an upgrade!
More Information
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Genre:Mythology
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Volatility:High
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Paylines:10
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Platform:Android, iOS, PC, PC
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Progressive Jackpot:No
