Book of 99 Slot Review

Book of 99 by Relax Gaming is a rare find: a high-volatility “book” slot with a staggering 99% RTP. Set amid ancient Greek legends, its 5 reels feature heroes, a cyclops and a harpy, while a persistent book-collection mechanic helps you trigger free spins more often. With a top payout of up to 12,070x your bet, the Book of 99 slot blends classic expanding-symbol gameplay with player-friendly math.

How to Play Book of 99

The reels sit between temple columns, with a book meter rising alongside them as you collect wild books. Jewelled card symbols cover the lower pays; premium character symbols deliver the bigger hits across 10 paylines.

Betting Options & Setup

• Reels/Lines: 5 reels, 10 paylines (left to right)
• Stakes: 0.10 – 100.00 per spin
• Devices: PC, iOS, Android, Windows mobile
• Quick Play/Autospin: Available via the control panel (region dependent)

Open the paytable to see stake-adjusted values and feature rules. The heroic character can pay from 1x up to 500x your total bet.

Book of 99 Symbols & Payouts

• Lows: Jewelled A–10 card symbols.
• Highs: Greek heroes and monsters (hero is the top payer).
• Book Symbol: Acts as both wild (substitute) and scatter trigger.

Book of 99 Features & Bonuses

Book Collection (99 Books)

Every time a book lands, the meter increases by 1—whether it helps a win or not. Reach 99 books to trigger free spins automatically.

Scatter Trigger

Alternatively, land 3 books in a single spin to launch the bonus immediately.

Free Spins with Expanding Symbol

• Random Special Symbol: Chosen at bonus start; it expands wherever it lands.
• Pays Anywhere: Expanded symbols don’t need to be adjacent to count.
• Retriggers: 3+ books during the bonus award extra free spins.

Book of 99 RTP, Volatility & Max Win

• RTP: 99% (exceptionally high)
• Volatility: High
• Max Win: Up to 12,070x (as much as 1,207,000.00 at 100.00 stake)

The unusually high RTP means stronger long-term value, but the high volatility still brings swingy sessions.

Book of 99 Verdict

The Book of 99 online slot keeps the beloved “book” formula—wild/scatter books and an expanding special—while adding a smart 99-book collection that nudges you toward the bonus. If you want classic mechanics with near-unbeatable RTP and serious upside, play Book of 99.