Book of 99: Slot with a 99% Return and a Book Counter
In short — our verdict: 7.6/10 — Relax Gaming publishes a 99% return for this game: two and a half points above the next published figure in this catalogue, and 14.82 above the lowest configuration in this catalogue, the 84.18% build of Book of Dead. The ceiling is a modest 5000x, and the studio prints it inside its free-spins description rather than flat.
A two-and-a-half-point gap in return is enormous, and this is the game that has it. Relax Gaming publishes 99% for Book of 99 and calls it a first of its kind. The nearest figures here are 96.50% on Book of the Fallen and the same 96.50% a casino publishes for Book of Oz in respin mode. We opened the studio's own demo on and read the rules. The house edge here is 1%. The catalogue norm is close to 4%.
7.6/ 10
- Return transparency7.0
- Ceiling clarity7.0
- Feature depth8.0
- Bet range8.0
- Documentation8.0
Table of contents
- Book of 99 Strengths and Weaknesses
- How This Book Slot's Return Compares
- A 99% Return Is Not a Rounding Difference
- The Book Counter That Opens the Round
- Expansion Depends on Which Symbol You Got
- What 99% Costs You Elsewhere
- Reading the Rules Without a Return Figure
- What the Client Told Us and What It Did Not
- Our Book of 99 Verdict and Rating
- Key Terms Used on This Page
- What Else Do Readers Ask
Book of 99 Strengths and Weaknesses
Pros: What Works Well
- Pro: A 99% published return, two and a half points above the next figure here — the house edge is 1% against a catalogue norm near 4%
- Pro: Two routes into free spins: the usual book trigger, and a counter that opens the round once you collect 99 books in the base game
- Pro: The expansion threshold differs by symbol value — two for high payers, three for low ones — a condition we have not seen elsewhere in this catalogue
- Pro: The bet range is published: €0.10 to €100
Cons: What Holds It Back
- Con: Volatility is not published at all, and for a 99% game that is the number a reader most needs
- Con: The ceiling is 5000x, modest next to the 30,338x on Book of Shadows — and Book of the Fallen returns 96.50% at the same 5000x, so the low ceiling is not what pays for the high return
- Con: The client prints no return figure on any rules screen we read, so the 99% rests on the studio's product page alone
- Con: We read five of about nine rules screens in the client and stopped there, so the reading behind this page is partial and says so
How This Book Slot's Return Compares
| Game | Published return | House edge |
|---|---|---|
| Book of 99 | 99% | 1.0% |
| Book of the Fallen | 96.50% | 3.5% |
| Book of Shadows | 96.01% | 3.99% |
| Book of Dead (default build) | 96.21% | 3.79% |
| Book of Ra Deluxe (Admiral Casino) | 92.13% | 7.87% |
Figures current as of ; the operator's live terms prevail.
A 99% Return Is Not a Rounding Difference
Relax Gaming publishes 99% and describes the game as a first-of-its-kind 99 RTP Book slot. Set against the next published figure here the gap is two and a half points, and against the lowest configuration in this catalogue — the 84.18% version of Book of Dead — it is 14.82. That sounds small and is not: the house edge falls from roughly 4% to 1%.
Put it in stakes rather than percentages. €100 wagered through this game expects to lose €1; the same stake through Book of Ra Deluxe at the 92.13% Admiral Casino UK publishes expects to lose 7.87% of it. The published figure is the whole argument for the game.
The Book Counter That Opens the Round
Among the titles whose rules we could read, free spins usually have one way in: land three books. Two of the four have a second way, and this is the only one where the second way is free. The usual trigger works. A counter on the left of the reels also tracks books collected during the base game: reach 99 and the round opens.
It changes how a session feels rather than how it pays. Progress accumulates instead of resetting, which is unusual for the genre. The studio's own copy ties the 99 to the return rather than to the counter, calling it "a first-of-its-kind 99RTP 'Book of' slot".
Expansion Depends on Which Symbol You Got
The free-spins rules carry a condition we have not seen elsewhere in this catalogue. One of nine regular symbols is chosen at random for the round. Expansion then requires "2 for high paying symbols and 3 for low paying symbols". After that the symbol covers the reel and pays across ten lines regardless of position.
A cheap symbol therefore needs more of itself to do anything, which quietly offsets the luck of the draw. The rules add one more line about wilds: they are disregarded for the expanded symbol's payout. Whether a wild counts towards the two- or three-symbol threshold the client does not say.
What 99% Costs You Elsewhere
The ceiling is 5000x, printed inside the studio's description of the free-spins round, against 30,338x on Book of Shadows — six times lower. That is not the price of the higher return: Book of the Fallen returns 96.50% and caps at the same 5000x. What the pair does describe is a different shape of game.
Relax Gaming publishes no volatility for this title, and that is the real omission. A 99% game could be built flat or spiky, and the studio leaves that unanswered while publishing the figure that sells best.
Reading the Rules Without a Return Figure
We read the rules screens in the client. The general conditions are unusually complete: incomplete rounds resolve automatically after two days, the bet locks once a spin starts, and the English rules prevail if a translation disagrees.
What is absent is the return. The client runs with a Maltese jurisdiction code, which on Play'n GO's client is precisely the condition that prints a percentage, and here nothing appears. The 99% is the studio's claim about its own game, published on its own page.
What the Client Told Us and What It Did Not
| Read in the client | Value |
|---|---|
| Free spins awarded | 10 on trigger, 10 more on 3+ wilds, no stated limit |
| Expansion threshold | 2 symbols for high payers, 3 for low payers |
| Return figure | Not on the rules screens we read, five of about nine |
| Bet on open | 2.00, balance 5,000.00 play money |
Our Book of 99 Verdict and Rating
Key Terms Used on This Page
- Book counter
- The running tally of books collected in the base game; reaching 99 opens free spins without the usual trigger.
- Expansion threshold
- How many of the chosen symbol must land before it covers a reel — two for high payers, three for low ones.
- House edge
- What the operator keeps over the long run, which is 100% minus the return: 1% here against roughly 4% elsewhere in this catalogue.
- Jurisdiction code
- A market marker in the game launch URL; on some studios' clients it is what makes a return figure appear on the rules screen.
Deposits and identity checks stay on the operator's own secure site.
Related Reading
Elsewhere in this catalogue, from the same section first:
What Else Do Readers Ask?
Two of these answers come from the studio's page and two from the client we opened.
Is the Book of 99 RTP really 99%?
Yes, as published. Relax Gaming prints 99% on its own product page, and on the five rules screens we read the client showed no return figure at all.
What is the maximum win?
5000x the bet, and Relax Gaming prints it inside its description of the free-spins round rather than as a flat ceiling. That is modest next to the 30,338x Nolimit City publishes for Book of Shadows.
How do you trigger free spins?
Two ways, and the second is unusual: the ordinary three-book trigger, or a counter that opens the round once you have collected 99 books in the base game.
Does every chosen symbol expand the same way?
No. The client sets two thresholds: a high-paying symbol expands with two on screen, while a low payer needs three before it covers the reel.
What did we actually open to check this?
We open the studio's own demo, read the rules screens it serves, note what the client prints, and attribute anything it does not print to whoever published it.