Real screenshot from our demo test, 2 Nov 2026
Relax GamingReleased 4 May 2021
Book of 99 Demo & review
A 10-line book slot with a 99.00% RTP in its rules, where three Book WILDs or a meter of 99 collected WILDs start free spins with one expanding symbol.
Written by Hampus GravePublished 5 Nov 2026
Play money · no sign-up · no deposit
- RTP
- 99%
- Volatility
- High
- Grid
- 5x3
Play Book of 99 for real at YEET
FluxPlays verdict
Our verdict
Only if you play long sessions and like book games. Every Book WILD in the main game fills a 99-step meter, so even the spins without a bonus move you toward one, and the stated RTP is the one in the name. The drawback is the round itself: one random expanding symbol, which pays little when the draw lands on a card rank.
Who it suits
Play this if…
- Long-session book players: every Book WILD counts toward a free spins round, even without the other two
- RTP-minded players: the figure in the name is the RTP the game states for itself
- Learners: ten lines, one WILD and one round make the book formula easy to follow
Skip this if…
- Bonus buyers: nothing can be bought, so the Books and the meter are the only ways in
- Short-session players: in our test the base game paid on about one spin in five, and three Books were slow to line up
- Max-win hunters: the rules name no ceiling, and a card rank drawn as the special symbol caps a round's upside
Where to play Book of 99
Book of 99 is available at these casinos we have tested and reviewed. How we test casinos
YEET
18+ · T&Cs apply
SafeCasino
FluxPlays score 7.5
Skrill withdrawal paid out in 18 hours in our test
400% up to €4,000 + 1,200 free spins
- 40x wagering
- min deposit €10
- 30 days
400% welcome package up to 4,000 over four deposits, each 100% up to 1,000 plus 300 free spins. 40x wagering on bonus and free spin winnings. Minimum 10 to activate, 200 for the full 300 spins. 30 day validity. Free spins run on Pragmatic Play games.
18+ · T&Cs apply · Offer checked 7 Oct 2026
Betlabel
FluxPlays score 7.0
E-wallet payout inside 24 hours in our test
200% up to €1,500 + 150 free spins
- 35x wagering
- min deposit €10
- 7 days
200% welcome package up to 1,500 plus 150 free spins over four deposits: 100% up to 300 + 30 FS, 50% up to 350 + 35 FS, 25% up to 400 + 40 FS, 25% up to 450 + 45 FS. 35x wagering, 7 day window. Minimum 10 first deposit, 15 thereafter. Crypto deposits are not bonus eligible.
18+ · T&Cs apply · Offer checked 7 Oct 2026
These are affiliate links: we earn a commission if you sign up through them. It never changes our scores. Affiliate disclosure
Book of 99: Full Review
Book of 99 gives a book slot two ways into its free spins: three Book WILDs on one spin, or 99 of them collected one at a time on a meter above the reels. Its rules set the RTP at 99.00%, the number in its name. Relax Gaming released it in May 2021, and it suits book players who settle in for long sessions rather than chasing a quick bonus.
Book of 99 game information
- Provider
- Relax Gaming
- Release date
- 4 May 2021
- Grid
- 5 x 3 (reels x rows)
- How it pays
- 10 paylines
- RTP
- 99.00%
- Volatility
- High
- Bet range
- $0.10 to $100
- Bonus buy
- Not available
How Book of 99 works
Ten fixed lines run across five reels of three rows, paying from reel 1, and only a line's top win counts. The Book is the WILD and also the trigger, replacing all symbols but the expanding one of the free spins. The hero tops a short paytable, and the four character symbols pay for two in a row.
| Book of 99 symbol | Pays for 5 / 4 / 3 / 2 at $1 |
|---|---|
| Hero | $500 / $100 / $10 / $1 |
| Hooded woman | $200 / $40 / $4 / $0.50 |
| Cyclops, horned woman | $75 / $10 / $3 / $0.50 |
| A and K | $15 / $4 / $0.50 / none |
| Q, J and 10 | $10 / $2.50 / $0.50 / none |
The top of the rules: the 99.00% RTP and the character pays at our 1.00 bet. FluxPlays demo test, 2 November 2026.
How the features connect:
- Every Book WILD that lands in the main game moves the meter one step toward 99.
- Three or more Books on one spin trigger the free spins at once.
- A full meter triggers the same free spins, played at your average bet.
- In free spins one random symbol expands, and three more Books extend the round.
The free spins are the feature, and the meter is a second road to them. It does not change what the round does, only how often you reach it.
How the collection meter works
The meter starts at 0 and gains a step for each WILD in the main game. At 99 it triggers free spins and resets, and any overflow carries over, so 101 WILDs leave it at 2. If a spin lands three Books and fills the meter at once, the Book-triggered round plays first.
The bet for a meter round is the weighted average of the bets you played while each WILD was collected, rounded to a multiple of the minimum bet by chance. The rules' own example: an average of 1.2 times the minimum plays at twice the minimum one time in five, and at the minimum otherwise. Rounds started by three Books play at the bet of that spin.
The meter at 49 of 99 after 140 of our spins. FluxPlays demo test, 2 November 2026.
Book of 99 free spins: how they trigger and what expands
Three or more Books anywhere award ten free spins, and one of the nine regular symbols is picked at random to be the special symbol for the round. Normal line wins pay first. Then, if enough special symbols are on screen, two for a character or three for a card rank, they expand over their reels and pay on all 10 lines wherever they sit. WILDs do not count toward that payout, and three more Books add ten more.
So the draw decides the round. By the paytable, two heroes expanded pay $10.00 a spin, while a card rank needs three reels and then pays half that. Our round drew Q and showed the second case: on the last free spin Q covered reels 2, 3 and 5, and three Qs on all 10 lines paid $5.00.
Free spin 10 of 10: Q expanded on three reels, and the round total settled at 27.50. FluxPlays demo test, 2 November 2026.
Book of 99 RTP, volatility and max win
The RTP appears twice in the rules and again as a badge on the intro screen. Neither the rules nor Relax's game page gives a volatility label, and review sites agree on High.
No cap appears anywhere in the game, and listings disagree on the top win by thousands of times the bet, so the table leaves it out. What the paytable does show is where a big round comes from: a character drawn as the special symbol, since it expands from just two reels.
Our Book of 99 demo test
FluxPlays demo test
2 November 2026, demo running 99.00% RTP
Base game spins
100
at $1 per spin
Staked
$100
Paid back
$28
28% of stake, -$72
Winning spins
21 of 100
21% of spins paid something
Biggest win
$10 (10x)
a line win, from the server log; Books landed on 30 of the 100 spins and the meter stood at 30 of 99, with no free spins in the logged spins
Free spins triggered
0
natural triggers in the session
Played on Relax Gaming's public fun-mode client (build 2.0.5) on 2 November 2026, in FUN credits read as dollars, from a 5,000 balance. The demo opened at 2.00 and was lowered to 1.00 for every spin. The game has no buy or paid mode. The 100 logged spins returned 28.00 (4,928.00 on the server). We then played 131 more spins at 1.00 to see the free spins: three Books on the 231st spin paid 13.00, and the 10 free spins with Q expanding added 14.50, 27.50 in all. That extra session staked 131.00 and returned 56.00, ending at 4,853.00 on screen; the meter read 76 of 99.
The meter was the steady part of the session. Books landed on 30 of our logged spins, almost always one at a time, so the meter read 30 when they ended and three Books never arrived together. Only 21 of those spins paid, none of them more than ten times the stake.
To see the free spins we kept playing at the same bet, outside the test card. Three Books came on the 231st spin of the session with the meter at 73, and the trigger spin paid $13.00. Q was drawn as the special symbol, and the round's total came to $27.50 with the Q expansion above.
The trigger on spin 231: ten free spins with Q as the special symbol. FluxPlays demo test, 2 November 2026.
A meter round never came, and neither did a character expansion. Amounts are in the demo's FUN credits, counted here as dollars. A session this size shows how the meter moves, not what the game returns over time.
Is Book of 99 worth playing?
One thing makes Book of 99 worth a look: the return in its name, backed by a meter that keeps a long session moving toward free spins. The round itself is a plain book feature with one expanding symbol, and a card rank drawn as that symbol makes for a small bonus.
Pick Book of Dead for the best-known version of the same expanding-symbol round, with a stated 5,000x cap. Choose Book of 99 for the higher RTP and a second route to the bonus that rewards time spent rather than luck on one spin.
In the demo, watch the meter for a few dozen spins before judging the game. Its pace tells you how long a meter round takes at your bet.
Frequently Asked Questions
What is the RTP of Book of 99?+
The rules give 99.00%, and the game shows it twice in its rules and again as a badge on the intro screen. That is the figure for the whole game, as there is no buy or paid mode with a separate return.
How does the collection meter work in Book of 99?+
Every Book WILD in the main game adds one step. At 99 the meter triggers ten free spins at the average bet you played while filling it, then resets, keeping any overflow. In our session it moved 76 steps in 231 spins.
How do you trigger free spins in Book of 99?+
Land three or more Book WILDs anywhere on one spin, or fill the 99-step meter. Either way you get ten free spins with one random special symbol that expands, from two reels for a character or three for a card rank. Three more Books add ten more.
What is the max win in Book of 99?+
The rules do not state one, and listings give figures thousands of times the bet apart, so we leave it out. The biggest rounds come from a character drawn as the special symbol, since two of them already expand and pay across all 10 lines.
More slots like Book of 99
Book of Power
Relax Gaming
7.1 / 10
Comments
Played it, tried it or have a question? Share it with the community under this slot page.