Book of 99 takes the familiar book-slot formula and gives it a sharper hook. You still get free spins and a random expanding symbol, but there’s a second route in too: collect 99 book symbols in the base game, and the bonus opens anyway. If you like simple rules with a real chase underneath, this one is worth a look.
last updated 29 May 2026
Book of 99 Pokie Review
Highest RTP
God-Themed
Ancient-Themed
Quick Facts
RTP
99.0%
Volatility
High
Provider
Relax Gaming
Min Bet
AU$0.10
Max Bet
AU$100
Max Win
12,075x
Free spins
Bonus game
Wild symbol
Scatter Symbol
Multiplier
Symbol Stacked
Jackpot Game
Slot reels
5
Slot lines
10 fixed paylines
Release Date
2021
Page contents
Game Overview
Book of 99 is a 5-reel, 3-row Relax Gaming pokie built on 10 paylines and a very familiar “book” structure, but it adds one mechanic that changes how the base game feels. The headline facts are easy enough: RTP is listed at 99%, volatility is high, bets run from $0.10 to $100, and the bonus round awards 10 free spins with a randomly chosen expanding symbol. Where it breaks from standard book-slot traffic is the collection meter on the left. Every book symbol that lands in the base game is saved, and once you collect 99, you trigger the same 10-spin feature even if 3 books never land together. So yes, this is still a free-spin chaser — just one that gives you a second path in, which matters a lot over longer sessions.
Game Features & Mechanics
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Ten Payline Layout
This is fixed line play on 10 paylines, paying left to right. No extra grid tricks, no cascades, no side game clutter — just classic reel maths underneath.
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Two Bonus Triggers
You can trigger free spins in 2 ways: land 3 book symbols on a spin, or collect 99 books in the base game meter.
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Random Expanding Symbol
Before free spins begin, 1 regular symbol is picked at random. During the feature, that symbol can expand to cover full reels and lift line wins fast.
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Bonus Retriggers
Land 3 or more book symbols during free spins, and you get 10 more spins. The chosen expanding symbol stays the same for the extended feature.
Technical Specifications
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Volatility Level
Book of 99 is a high-volatility pokie. The RTP looks huge, but that does not flatten the swings — the bigger moments are still tied to free spins and retriggers.
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RTP Explained
The listed RTP is 99%, which is the main talking point here. Treat that as a long-run theoretical figure, not as a promise for any single session.
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Bet Range
Bets start from $0.10 to $100 per spin. If your casino shows different limits, go with the lobby settings in front of you.
Paytable & Symbol Values
The base symbol set is clean: 10, J and Q sit at the bottom, and each pays 0.5x for 3, 2.5x for 4, and 10x for 5 on a line. K and A are the next step up at 0.5x, 4x and 15x for 3, 4 and 5. The premium characters start with Lamia and Cyclops, both paying 0.5x for 2, then 3x, 10x and 75x for 3, 4 and 5. Pythia improves that to 4x, 40x and 200x. Apollo is the top regular symbol and pays 10x, 100x and 500x for 3, 4 and 5. Because this is a 10-payline slot, symbol quality matters more than symbol count - especially once free spins choose what can expand.
Special Symbols
Book Wild Scatter
The book does 2 jobs at once. It substitutes for regular symbols in line wins, and 3 or more books anywhere trigger 10 free spins.
Selected Expanding Symbol
At the start of free spins, 1 regular symbol is chosen to expand. Premium symbols need 2 on a reel area to expand; royals need 3.
Graphics, Animations & Sound Design
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Graphics
Book of 99 uses an ancient Greece theme with a darker, weathered look. The reels feature gods and monsters, but the screen never feels overloaded, and the symbols stay clear.
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Animations
The base game keeps things fairly quiet. Most of the movement comes from landing books, the collection meter rising, and the bonus reveal of the chosen expanding symbol.
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Sound Design
The audio goes for a dramatic myth feel rather than constant noise. You hear stronger effects around book lands, bonus entry and better wins, but it never gets overdone.
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Visual Feel & Interactivity
Key information is easy to follow: paylines, meter progress, bonus state and the selected symbol. The layout stays clean, so the game feels simple to track.
Game Gallery
Book of 99 on Mobile Devices and Other Platforms
Book of 99 runs cleanly across desktop and mobile formats, which suits the way the game is built. This is not a feature pile-up with nested menus and side modifiers, so the smaller screen experience stays readable without much compromise. The reel set is compact, the paytable is straightforward, and the book meter remains visible enough to matter while you play. On touch devices, the pace feels natural because there is very little interface clutter getting in the way. The one thing worth noting is that this is still a detail-led slot when free spins begin. Once the expanding symbol is selected, it helps to have enough screen space to read the reels comfortably, especially if you are checking symbol values and feature progress between spins.
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Android
Android suits Book of 99 well because the layout is light and the controls are simple. You are not squeezing through layered bonus panels or overloaded side mechanics.
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iOS
On iPhone and iPad, Book of 99 keeps its core information visible without feeling cramped. That matters here because the meter and selected feature symbol both deserve attention.
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Tablet
Tablet is probably the nicest middle ground. You get more room for the paytable, clearer reel visibility during expansions, and a cleaner overall view of the bonus setup.
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Desktop
Desktop gives the clearest read on everything at once: paylines, meter progress, paytable values and feature flow. If you like checking details as you play, this is the easiest format.
Optimal Gameplay Tips
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Use Stable Connection
EssentialBook of 99 is simple to run, but a steady connection helps the reels load properly and keeps the bonus, retriggers, and book meter updates smooth.
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Landscape Mode Recommended
RecommendedLandscape view gives the reels and side meter more room. It is the easier way to follow book collection and read expanding-symbol results during free spins.
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Audio Settings
OptionalThe sound design is not essential for play, but it does help with the bonus atmosphere. If you use audio, a moderate level is usually enough.
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Full Screen Mode
RecommendedFull screen makes the reel area clearer and helps the interface feel less cramped. That is especially useful on smaller devices once free spins begin.
About Relax Gaming — The Developer Behind the Game
Relax Gaming is one of those providers that tends to keep its maths-led identity even when the themes shift around. The company says it was founded in 2010 with the goal of simplifying global content delivery, and its wider catalog now spans in-house slots, jackpot products, poker and bingo. It also runs major distribution channels for third-party studios through Powered By Relax and Silver Bullet. What matters for Book of 99 is that Relax usually does not build games around empty decoration first and rules second. Even in titles with stronger presentation, there is normally a very clear mechanical centre.
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Founded for Speed
Relax Gaming was founded in 2010 to simplify worldwide content delivery, which tells you a lot about the company’s technical-first identity.
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Strong In-House Games
The provider’s own portfolio includes a broad list of internal slot releases, not just aggregated content from partner studios.
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Wide Market Reach
Relax highlights global reach and regulated-market growth as part of its strategy, with licences and distribution across multiple jurisdictions.
Final Verdict
Why It’s Worth Playing
- We like the dual-trigger setup because the base game can still build toward free spins without 3 books
- The 99% RTP is the obvious draw and gives this pokie a stronger long-run value story than most book-style releases
- Free spins stay simple, ideal for a feature-led slot without extra rule clutter.
- The book symbol matters in more than one way, acting as both scatter and wild rather than a one-job trigger
- The expanding symbol feature can still hit hard, especially when the bonus chooses one of the stronger premium characters
Things to Consider
- High volatility is still high volatility, so the RTP headline does not protect you from long flat stretches
- The max win is 5,000x, which is decent, though not especially wild beside newer high-variance releases
- If you are tired of book slots as a format, this one may still feel too close to the usual template
Overall Rating
8.6
Bottom Line
We’d call Book of 99 a smart twist on a very familiar format, not a total rewrite of it. The core game is classic book-slot territory: 5x3 reels, 10 paylines, a book wild scatter, 10 free spins and a randomly selected expanding symbol. What makes it more interesting is the second bonus route, where collected books in the base game eventually trigger the feature on their own. That one change gives the slot a bit more purpose between bonuses. The 99% RTP is the headline, but the game still swings hard and lives on feature outcomes. If you like book pokies and want one with a better long-run number, this is an easy slot to shortlist.
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Frequently Asked Questions
Is Book of 99 played on paylines or ways?
Book of 99 uses 10 fixed paylines on a 5-reel, 3-row layout. Wins pay from left to right, so it plays more like a classic structured pokie than a modern ways slot.
Is Book of 99 a high RTP pokie?
Yes. The official listed RTP is 99%, which is unusually high for an online pokie. That is a theoretical long-run return, though, so it does not mean every short session will play kindly.
How do free spins trigger in Book of 99?
There are 2 bonus routes. You can trigger 10 free spins by landing 3 book symbols, or by collecting 99 book symbols through the base-game meter. Both lead into the same feature.
What happens during the free spins feature?
Before the bonus starts, 1 regular symbol is chosen at random. During free spins, that symbol expands to fill reels, and 3 or more books can retrigger another 10 spins.
What is the max win in Book of 99?
Relax Gaming’s official product page states win potential up to 5,000x the bet. That puts it in a respectable range, though it is not trying to compete with huge modern max-win slots.
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