Book of 99 is a Greek-mythology “Book of” slot from Relax Gaming, best known for one thing: an unusually high 99% RTP. This page sets out the plain facts: what it is, how it plays, its RTP, and how the features work — without hype.
It is written to inform, not to promote. Nothing here recommends playing or depositing, and a high RTP is not a reason to play. Slots are games of chance built with a house edge, so over time they are designed to return less than is staked.
What It Is
Book of 99 is a video slot from Relax Gaming, released in 2021. It runs on a 5-reel, 3-row grid with 10 fixed paylines — the standard “Book of” format — with a Greek-mythology theme (Apollo is the top-paying symbol) on a temple backdrop. The number in the title is the clue to its headline feature: the RTP.
It sits in the same broad genre as other “Book” slots we cover, such as Book of Dead and Book of Rebirth, but what sets it apart is its maths rather than its theme.
How It Plays
Set your bet (roughly $0.10 to $100) and spin; wins pay for matching symbols across the 10 lines from the left. As with all “Book” slots, the game is built around reaching the free spins — and here there are two ways to get there.
RTP, Volatility and Max Win
The RTP is the reason this game exists. At 99.00%, it’s exceptionally high — most slots sit around 95–96%, and anything above 97% is rare, so 99% is genuinely unusual and represents better long-run value. That’s a real positive, and worth understanding clearly.
But it’s just as important to understand what it doesn’t mean. 99% is still below 100%, so the house keeps roughly a 1% edge — the game is not “in your favour.” And the volatility is very high (rated 5/5), with wins landing only about one spin in three, so you’ll see big swings and long dry spells regardless of the generous RTP. In practice, most sessions still lose; the strong RTP simply means the long-run cost is lower, not that winning is likely. Our guide to RTP explained covers this distinction. The maximum win is around 12,075× your stake — solid for the volatility level, but a rare theoretical ceiling.
Playing From New Zealand
You’ll find Book of 99 at online casinos that carry Relax Gaming titles and accept New Zealanders. Rather than naming specific sites, the important thing is to check the operator itself: the legal backdrop changed in 2026, when the Online Casino Gambling Act 2026 created New Zealand’s first licensing system for online casinos, run by the Department of Internal Affairs (DIA). From 1 December 2026, only DIA-licensed operators may lawfully offer online casino games to New Zealanders. A game like this isn’t “licensed” in New Zealand — the casino offering it must be. Our overview of online casino licensing in New Zealand explains how that works, and you can browse more titles via our casino games section.
Practical Notes (Not a Strategy)
No strategy changes a slot’s odds — every spin is independent and random, and the bonus is never “due,” however long the dry spell. The high RTP is not a system: it doesn’t make winning likely, and it can’t be “used” to beat the game. A few honest pointers: understand that high RTP and high volatility both apply here — better long-run value, but big short-run swings; try the demo/free-play mode first; set a firm time and money limit before you start; and remember bonus funds and free-spin offers carry wagering requirements (our casino bonuses guide explains the fine print).
Staying in Control: Responsible Play in Aotearoa
A “99% RTP” headline can be read as a green light — but a generous return doesn’t make a slot safe, and the very high volatility here can still drain a bankroll through the long dry spells. Treat any slot as paid entertainment only — never as a way to make money or recover losses. Regulated operators must provide control tools such as deposit limits, reality checks and self-exclusion. Our guide to self-exclusion tools explains how they work.
Free, confidential help is available in New Zealand at any time — you do not need to be in crisis to use it.
Factual information disclaimer
This article is provided for general information only. It describes the features and publicly reported facts of the Book of 99 slot; it does not encourage gambling, does not recommend playing this game or depositing with any operator, and is not legal, financial or professional advice.
Gambling involves financial risk and can be harmful. RTP figures are long-run averages, not a promise of returns — even a 99% RTP leaves a house edge, and the maximum win is a rare theoretical outcome. Game details, RTP and availability can vary by casino and change over time — always check the in-game information before playing.
If gambling is affecting you or someone you know, free and confidential support is available: the Gambling Helpline Aotearoa on 0800 654 655 or at gamblinghelpline.co.nz, and the New Zealand regulator, the Department of Internal Affairs, at dia.govt.nz.
What is the RTP of Book of 99?
It’s 99.00%, which is exceptionally high — most slots sit around 95–96%. That’s better long-run value than almost any other slot, but it’s still below 100%, so the house keeps roughly a 1% edge.
Does a 99% RTP mean I’ll win?
No. RTP is a long-run average measured over millions of spins, not a prediction for your session. The game is also very high volatility, so most sessions still lose — the high RTP just lowers the long-run cost, it doesn’t make winning likely.
How do the free spins work?
There are two routes: landing three or more scatters awards 10 free spins with a random expanding symbol, or you can collect 99 Book symbols on the Wild Collection Meter to trigger the bonus. Three or more books during the round add 10 more spins.
What is the maximum win?
Around 12,075× your stake — solid for a game of this volatility, but a rare theoretical ceiling reached only through an exceptional bonus, not an expectation.
Where can I get help if gambling becomes a problem?
Free, confidential support is available in New Zealand through the Gambling Helpline Aotearoa on 0800 654 655. Support is available at any time, and you do not need to be in crisis to reach out.
