Dual wild scatter
The Book substitutes for standard pay symbols, counts as scatter, and advances the collection meter.
Relax Gaming · Greek book · 99% RTP
Book of 99 Slot Review: Play Demo and Experience 99% RTP
Ancient Greek mythology receives a mathematical overhaul in the Book of 99 slot machine by Relax Gaming. Renowned as a landmark release in online casino history, this title features an industry-leading 99.00% Return to Player (RTP) alongside classic expanding symbol mechanics. Beyond traditional scatter triggers, the developer introduces a wild collection meter that guarantees entry into the bonus round after collecting 99 books.
99%
Game specifications
ProviderRelax Gaming
Layout5×3
Paylines10 fixed
RTP99.00%
VolatilityHigh
Max win5,000×
Feature99-book meter
Free games3 books or 99 books → 10
Bet range$0.20–$100
Release4 May 2021
Inside Book of 99: Relax Gaming's High-RTP Legend
Relax Gaming redefined expectations for “Book of” grid slots when launching this ancient Greek title. While most releases operate with returns around 96.00%, the team engineered a return that pays back $99 for every $100 wagered over long-term play. Beyond this statistic, the studio integrated a dual-trigger mechanic. Players no longer rely solely on landing three book scatters; every book symbol landing during base spins fills a step on a collection meter, ensuring guaranteed feature access over extended sessions.
Greek Odyssey: visuals, animations, and mythological audio
Sensory presentation transports players to ancient Homeric shores. Set against a dark forest framed by marble pillars and glowing torches, the 5×3 grid showcases artwork of Odysseus and mythological beasts. Winning connections trigger smooth animations, while the collection meter glows with golden energy whenever books fly into its counter. A dramatic score with sweeping strings heightens tension during collection triggers.
Unmatched specs: 99% RTP, volatility, and maximum payouts
The official Book of 99 RTP of 99.00% is a massive advantage. Because volatility is high, win distribution focuses heavily on the bonus round. Understanding that high-volatility / high-RTP balance helps manage wagers as you pursue the 5,000× stake max win.
| Specification | Parameter |
|---|---|
| Developer | Relax Gaming |
| Return to Player (RTP) | 99.00% |
| Volatility | High |
| Grid | 5 reels, 3 rows |
| Paylines | 10 fixed |
| Betting limits | $0.20–$100.00 per spin |
| Maximum win | 5,000× total stake |
How to play: core rules, 10 paylines, and controls
Navigating Book of 99 is straightforward on desktop and mobile browsers:
- Adjust wager: choose stake sizes from $0.20 to $100.00.
- Consult paytable: open the menu (“i”) to inspect symbol values and line rules.
- Toggle quick spin: enable turbo mode to speed up reel spins.
- Configure autoplay: program 10 to 1,000 automated turns with custom stop limits.
- Start spinning: click the central button. Wins calculate left to right along 10 fixed paylines starting from reel 1.
99 collection
Every book in the base game adds +1. Collect 99 books to trigger 10 free spins at the average wager used during collection.
Expanding symbols
A random icon is chosen for the feature. Enough copies expand to cover full reels and pay all 10 lines.
Expanding myths: paytable, collection, and free spins
Low-value royals 10 through A are stylized in Greek lettering and return 0.5× to 15× total stake for five of a kind. High-value symbols are the Female Warrior, Cyclops, Lamia, and the Male Hero. The Male Hero tops the paytable at up to 500× wager for five matching icons along a line. The Book is both wild and scatter.
Relax Gaming added two pathways into expanding free spins. Landing 3 or more Book scatters — or collecting 99 books — awards 10 free spins. A random icon is selected as the expanding symbol. When enough copies land, they expand to cover full reels and pay across all 10 lines. Three or more scatters inside the feature retrigger 10 extra spins.
Engineered with HTML5, the game scales across iOS and Android screens. You can enjoy free play in demo mode without downloading an app. The touchscreen interface keeps visuals crisp and controls smooth in portrait or landscape.
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Book of 99: pure masterpiece or overhyped legend?
Pros
- Market-leading 99.00% official RTP.
- Guaranteed bonus trigger via 99-book collection.
- Classic 5,000× max win with expanding symbols.
- Responsive touchscreen UI for mobile demo play.
Cons
- High volatility can cause dry spells during base play.
- Collecting 99 books requires disciplined bankroll management.
Smart play: responsible gaming and risk control
Navigating high-volatility slots requires discipline. Set deposit limits before you start. Budget your bankroll to sustain collection sequences, treat slot spins purely as entertainment, and never chase losses.
Combining a 99% RTP with a 99-book collection meter set a new standard for player value. Test the demo on this page before choosing where to play for real money.
Player reviews
Notes from temple sessions and the HTML5 demo.
★★★★★ 4.8/5
99% RTP is the reason I stayed. High vol is honest — dry base, then the expander covers reels and the 10 lines all pay. I size at $1 while the meter crawls.
★★★★☆ 4.3/5
Marble pillars and the torch forest look clean in portrait. Books flying into the 99 meter is the animation I wait for. Strings get tense on collection hits.
★★★★★ 4.6/5
Three books still beat the long walk to 99. When the hero expands, 5,000× feels possible. Retrigger of 10 extra spins saved a dry bonus.
★★★★☆ 4.2/5
Meter progress per bet level is real — I dropped stake and lost the count. Stay on one wager if you want the guaranteed 10 free games.
★★★★★ 4.5/5
Demo’d the dual trigger the week I found it. No bonus buy keeps the 99% math intact. HTML5 on iPhone, no app, same 5×3 as any classic book slot.
FAQ
Is there an instant Feature Buy or Bonus Buy option available in Book of 99?
No, Relax Gaming omitted a Feature Buy option to preserve the official 99.00% RTP math model and focus on the natural collection meter.
Can you retrigger additional Free Spins during an active bonus round in Book of 99?
Yes, landing 3 or more Book Scatters during an active round awards 10 additional free spins with the same expanding symbol.
What happens to your collection meter progress if you change your bet size midway through filling it?
Meter progress is saved individually per bet level. Changing your bet size restores the saved book count for that specific wager.
Is Book of 99 optimized for single-handed portrait mode play on modern mobile smartphones?
Yes, the adaptive HTML5 layout automatically adjusts button positions for comfortable one-handed portrait operation on mobile devices.
What happens to your 99 Book collection progress if a session terminates due to network disconnection?
Your collection progress is stored on casino servers. Upon re-logging, your book count and bet levels remain intact.