Book of 99 Slot in UK
Book of 99 is a high-RTP slot from Relax Gaming, built around a rare 99.00% RTP, bets from £0.10 to £100, 10 free spins and win potential up to 5,000x your stake. This page will cover the main game facts, bonus mechanics, expanding symbols and where UK players may find the slot at licensed online casinos.
At our site, you can play Book of 99 by Relax Gaming, a “Book of” slot available to UK players with a 99% RTP. We first reviewed this game in 2021, and it still stands out for having the highest RTP in the Book of series.
Play Book of 99 Here
This page is currently in setup mode. Soon, you will find updated information about Book of 99, including the slot’s main features, provider background, and details on licensed UK casino platforms where the game may be accessible.
Info Table
Book of 99 follows the familiar Book-style slot format, but adds a collection mechanic that affects how the bonus round can be reached. UK players usually check this game for its simple structure, clear stake settings, and bonus-focused gameplay. The info table below collects the main technical details in one place, so you can compare the slot’s rules before opening the game.
| Slot | Book of 99 |
| Provider | Relax Gaming |
| RTP | 99% |
| Min bet | £0.10 |
| Max bet | £100 |
| Max win | 5,000x bet |
| Bonus trigger | 3 book symbols or collecting 99 books in the base game |
| Free spins | 10 free spins |
| Special feature | Expanding reel with random character |
| Release | 2021 |
Book of 99 uses a classic book-slot structure but adds two trigger paths for the bonus round. Free spins can start through 3 book symbols or by collecting 99 books during the base game. The special feature then expands one random symbol across the reel set, which makes the bonus round the main part to test before real-money play.
Book of 99 vs Book of Dead – Key Differences Explained
Book of 99 and Book of Dead use the same core Book-style setup: 5 reels, expanding symbols during free spins, and a high-volatility structure. The main difference is in the numbers. So the return profile is not the same. For UK players, the comparison usually comes down to RTP and risk level.
Two classic book slots – but very different gameplay styles
Both slots use the same core Book-style format, but they differ in risk profile. For UK players, the choice depends on whether you value longer playtime or a more aggressive payout model.
Book of 99 RTP & Key Features
We always highlight Book of 99 because is sincerely outstanding for a high-volatility slot. Over the long term, the game returns £99 for every £100 wagered, which gives our players significantly better value than most other Book of titles. This high return percentage combined with the potential for very large wins makes the slot stand out as one of the smartest choices for UK players who want both passion and strong mathematical value.
- RTP: 99% – the highest in the entire Book of series. This means the slot keeps more of every pound you wager in the long run compared to almost any competing title.
- Volatility: High – wins appear less frequently, but when they land they tend to be much larger, creating that classic Book of trembling our players love.
- Grid: 5×3 with 10 fixed paylines – the classic and easy-to-follow layout that has made Book of 99 slots so popular for years.
- Bet range: £0.10 – £100 per spin – perfect flexibility that suits both beginners who want to play small and high rollers who prefer maximum stakes.
- Maximum win: 12,075× your stake – at the highest bet this equals more than £1.2 million in a single spin, giving the game serious big-win potential.
- Hit frequency: ~29.83% – you can expect roughly one winning combination every 3.35 spins on average, which keeps the base game from feeling too dry.
These numbers are exactly why we recommend Book of 99 to our players who want potential for a major win while still enjoying one of the best theoretical returns in the category. The combination of a record-high RTP and strong maximum win ceiling makes this slot feel both fair and sincerely remunerating in the long run.
How to Play Book of 99
We made sure Book of 99 is as simple and fast to play as possible. Just register at our casino, make a quick deposit, and search for the game in the lobby.
- Create Your Account
Tap the prominent pink “SIGN UP” button on the homepage to begin the quick registration process.
- Enter Your Login Details
Fill in your email address and create a secure password on the first step of registration.
- Full Your Personal Information
Provide your first name, last name, phone number, date of birth, address, postal code and other required details on the second step, then tap “REGISTRATION”.
- Search for Book of 99
Open the search bar at the top and type “Book of 99” – the game icon will appear instantly.
- Launch and Start Playing
Tap on the Book of 99 thumbnail, set your stake from £0.10 to £100 and begin spinning the reels right away.
Book of 99 lets you play from £0.10 to £100 per spin. Its 5×3 reel setup and 10 fixed paylines give UK players a clear and familiar slot format.
Paytable Explained
We like the paytable in Book of 99 because it pays more often than many standard Book slots, while still keeping the win potential strong. Relax Gaming also lets high-paying symbols pay from two matches instead of the usual three. That makes the base game feel less rigid and a bit more active from spin to spin.
- High-paying symbols (Cyclops, Lamia and two Greek heroes) are the strongest and most valuable icons in the game. They pay from just 2 matches on a payline and can award up to 500× your stake when five identical symbols land together. These symbols are the main reason for the biggest regular wins and look spectacular when they expand fully across the reels during the bonus round.
- Low-paying symbols (10, J, Q, K, A) follow a more traditional structure and pay from 3 or more matches. Although the individual payouts are smaller, they appear more frequently and play an important role in keeping the balance steady, providing regular small wins while you wait for higher-value combinations or the Book trigger.
- The Book symbol is the star of the entire paytable. It works as both Wild and Scatter, substituting for all other symbols to help full winning lines and, most importantly, triggering the free spins bonus whenever three or more Books land anywhere on the reels.
All wins are calculated left to right across the 10 fixed paylines. This classic and transparent system makes Book of 99 very easy to understand and enjoyable for both full beginners and experienced players who appreciate clear, fair mechanics.
Book of 99 Bonus Features
Book of 99 has two bonus entry methods. You can trigger free spins in the standard way by landing 3 or more Book symbols, or by collecting 99 Book symbols during the base game. That second route makes the feature set different from a standard Book slot, because the bonus can build over time instead of depending only on one scatter hit.
| Feature | How It Works Book of 99 bonus |
| Standard Free Spins | 10 spins + one random symbol becomes Expanding (fills the whole reel) |
| 99 Book Collection | Every Book in base game adds to your counter; 99 Books = automatic 10 spins |
| Retrigger | +10 extra spins (Expanding Symbol stays the same) |
This dual bonus system is one of the main reasons Book of 99 bonus feels so fresh and remunerating for our players. Whether you trigger the free spins quickly or take your time collecting all 99 Books, the game keeps you hooked with constant progress and passion. It perfectly combines the familiar high-voltage trembling of the Expanding Symbol mechanic with the deeply satisfying feeling of working toward a guaranteed bonus.
How to Play with Smartphone
We have fully optimised Book of 99 for mobile play, so you can enjoy the same high-quality experience on your smartphone as you do on desktop. The game runs smoothly on both Android and iOS devices with sharp graphics, fast loading times and responsive touch controls. Whether you are on the train, at work or relaxing at home, you get the full 99% RTP, the full bet range and the same potential for a major win without any compromises.
- Open our casino website or app directly in your smartphone browser
- Log into your account or full a quick registration in under a minute
- Go to the slots section and search for “Book of 99”
- Once the game loads, tap the bet selector and set your stake from £0.10 to £100
- Adjust autoplay if you want, then tap the Spin button and start playing instantly
- The game 99 Book collection counter and Expanding Symbol feature work perfectly on mobile
Our mobile version of Book of 99 feels almost identical to the desktop experience – just perfectly adapted for smaller screens. You get the exact same gameplay mechanics, bonus features and maximum win potential of 12,075× your stake, giving you the freedom to play and chase big wins anywhere you want.adapted for smaller screens.
Play Demo Mode of Slot
We give our players the chance to try the full Book of 99 demo for free with a virtual balance of over £10,000. This lets you test the 99 Book collection system in real time, see how often the Expanding Symbol fills the screen, and experience the actual hit frequency of roughly one win every 3.35 spins before playing with real money.
About Relax Gaming
Relax Gaming is an established B2B iGaming supplier founded in 2010 by Patrik Österåker and Jani Tekoniemi. For UK-facing content, the main compliance point is that Relax states it is licensed and regulated by the UK Gambling Commission, and it also lists additional approvals including the Malta Gaming Authority. That makes the provider suitable for regulated-market positioning rather than offshore-only wording.
In terms of reputation, Relax has a strong industry track record. On its official news pages, the company says it has won awards such as Best Mobile Gaming Software Provider at the EGR B2B Awards, Casino / Slot Developer of the Year at the SBC Awards, and GGA Product Launch of the Year for Dream Drop Jackpots. Book of 99 itself was also named Slot to Watch at the 2021 CasinoBeats Game Developer Awards.
