Land the Books
Three or more Book wilds anywhere in one base-game spin start ten Free Spins at the triggering stake.
Read the full feature →
Independent player guide · fact-checked 22 July 2026
Book of99
A rare 99% RTP slot with two doors into the same expanding-symbol Free Spins feature: land three Books now, or collect your way to ninety-nine.
18+ · Fun-mode demo · Partner access is clearly labelled
Collection route0—99Every base-game Book advances the meter
Enter the archive ↓Game dossierVerified essentials
01 · RTP99.00%
02 · Maximum win5,000×
03 · Reels5 × 3
04 · Paylines10
05 · Bet range€0.10–€100
06 · Released4 May 2021
The number that made the game unusual
Why 99% is such a big deal.
Book of 99 launched as Relax Gaming’s first Book slot with a 99% RTP. Put simply, across a huge amount of play the game is designed to return €99 in prizes for every €100 wagered, leaving a theoretical €1 house edge.
Per €100 of turnover€99 designed for prizes€1 theoretical house edge
It is still not a promise for tonight. A €100 deposit does not turn into €99 on cue. Random results, sharp swings and the timing of Free Spins can leave one session far above or below that long-run average.
Read the full RTP and paytable guide →Published RTP99%1% house edge
Compare the same turnover
See what each RTP point is worth.
Turnover means every paid stake added together, including winnings you choose to spin again. It is much bigger than a starting deposit during a longer session.
Compare with another advertised RTP
Book of 99 · 99%€990theoretical prizes
€10 edge
Comparison · 96%€960theoretical prizes
€40 edge
Extra value in the long-run return+€30
more allocated to theoretical prizes at 99% across €1,000 of turnover than at 96%.
This comparison explains the published percentages; it cannot predict or smooth out your own results. Always confirm the RTP shown inside the live game before playing.
Real fun mode
Open the book before you risk a balance.
Launch Relax Gaming’s official demo right here. Explore the reels, watch the collection rail and open the paytable with demo credits—no account or deposit needed.
Official Relax Gaming launcher
Official fun mode
Open the real Book of 99
The game loads only when you choose to start it. No account, deposit or real balance is used inside this page.
Two feature entries
One chamber. Two ways in.
Both routes lead to ten Free Spins and a randomly selected expanding symbol, but the stake used by the feature is not calculated the same way.
Complete the collection
Every main-game Book adds one. At 99, ten Free Spins begin at a weighted average of the stakes used while collecting.
Understand the average →The promise inside the counter
Reach 99 Books. The feature starts.
The collection route does not ask the final spin to be a winner. Every Book wild that lands in the main game advances the counter, including Books collected on losing spins. When the counter reaches 99, ten Free Spins are awarded automatically.
The finish line is guaranteed. The journey to it is random.Book wild lands+1Win or lose, the symbol counts
Collection complete99The counter unlocks the feature
Automatic award10Free Spins with one expanding symbol
What it does not guarantee
Books still land randomly. The meter cannot promise that you will reach 99 within one budget, a set number of spins or before you choose to stop. The collection-triggered feature uses a weighted average of the stakes attached to the collected Books.
Open the 99-Book stake planner →The long route
Build your road to 99 Books.
Switch stakes, add the Books you collect and see how the eventual Free Spins stake changes. It is a useful what-if tool, not a crystal ball.
Your road to 99
See how every Book shapes the feature
Every collected Book remembers the stake used when it landed. Add a few groups below and you can see how that history shapes the eventual Free Spins stake.
Collected27of 99 Books
72 Books to go before ten Free Spins.
Stake attached to the next Book€0.50
Add Books collected at €0.50
Your collected Books
12 Books × €0.2015 Books × €0.50
Books remaining72
Estimated feature stake€0.37
Your progressStill collecting
Weighted averageΣ (Books × stake)÷27 collected Books= €0.37
Use this as a what-if guide to the published weighted-average rule. It cannot read a casino session or predict when Books will land, and the live game may round the final figure to an available stake step.
The payoff mechanic
See how expansion changes the screen.
A selected high symbol needs at least two instances; a low symbol needs at least three. Once qualified, reels containing it expand and can pay across all ten lines.
Try the expanding symbol
Turn matching symbols into full reels
Tap the grid to place the chosen feature symbol. Hit the required number and every reel carrying a match expands before the ten paylines are counted.
Activation rule2+ high-pay symbolsExpansion can pay on all 10 lines, even without a normal left-to-right connection.
Matches3
Reels affected3
What happensExpansion active
This hands-on example shows how expansion works; it does not recreate or predict real spins.
V
Read the screen
Five reels, ten fixed lines, one persistent left rail.
- Reel window. Winning combinations are read left to right across ten always-active paylines.
- Book wild. It substitutes for every regular symbol and also drives both Free Spins entry routes.
- Collection rail. Base-game Books move the count toward 99; the rail stays with you between paid spins in the game session.
- Feature choice. The game—not the player—selects one regular symbol to expand for the Free Spins round.
Know what landed
The paytable, without the guesswork.
The Hero tops the official €2 help-screen values, while A and K lead the card symbols. The Book has no regular line prize of its own—it is both the wild and the key to Free Spins.
Top displayed award1,000five Hero symbols · help screen shown at €2 current bet
Only the highest-paying combination on each line is paid. Wins across different paylines add together.
Open the complete paytable →The original release
Relax Gaming rewrote the Book format in May 2021.
Released on 4 May 2021, Book of 99 paired the familiar expanding-symbol setup with a standout return figure and a second, visible feature route. That combination—not mythology alone—is why the title still has a distinct search identity.
Player questions
Before you open the book.
01What is the RTP of Book of 99?+
The published theoretical RTP is 99.00%. It is a long-run mathematical figure, not a promise for a session.
02How do Free Spins start?+
Ten Free Spins are awarded by landing three or more Book wilds, or by filling the separate collection meter with 99 Book wilds from the base game.
03Do 99 collected Books guarantee Free Spins?+
Yes. Once the collection meter reaches 99 Book wilds, the game awards ten Free Spins even if the spins that built the meter were losing spins. What is not guaranteed is how quickly the 99 Books will land or how much play it will take to reach them.
04What happens in Free Spins?+
One regular symbol is chosen for the feature. When enough of that symbol lands, every reel containing it expands and can pay across all ten lines, even without the usual left-to-right connection.
05Is the Book of 99 demo real?+
Yes. The demo on this guide loads Relax Gaming’s official fun-mode launcher. It uses no real balance and may be unavailable in some locations.
06Can the 99 meter predict when I will win?+
No. It records collected Book wilds and provides a separate route into Free Spins. It does not predict spin results or guarantee profit.
Choose your next page
Study the feature. Try the real demo. Then decide.
Book of 99 is a game of chance. Its 99% RTP is meaningful over the long run, but no meter, symbol or session plan can make a random spin predictable.