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Relax Gaming has created a slot that combines two of the most popular themes in slots nowadays, the "Book of…" and the Ancient Greece theme. Such a combination means nothing but success since the Book of 99 slot is about to make a real boom across the industry.
You may not assume from the title right away, but the title is related to the mind-blowing RTP this game offers. Book of 99 offers a staggering 99.00% RTP, and that’s its strongest suit, and one of the main differences between it and its Play'n GO's counterpart – the Book of Dead slot. Add to that the fact that the highly volatile slot comes with a pretty standard 10-payline, 5 reels grid, and you’ve got yourself an already exciting slot to play. But, you should know that you’ll be showered with Free Spins and Expanding Symbols, as well as the Wild Collection feature, taking you to wins of up to 12,070x the stake. Ready to explore the Greek temples and meet the villains and heroes of the glory Ancient Greece days?


Book of 99 unfolds on a temple wall backdrop with a 5x3 reel grid. The left pillar shows the Wild Collection Meter, while the right holds controls like Quickspin, bet settings (0.10-100 credits), Play, Autoplay, and the paytable button.
Symbols include Greek-styled Royals for low pays and ancient heroes or villains for big wins of 75x-500x your stake. The Book symbol acts as both Wild and Scatter, substituting for other symbols and filling the Wild Meter. Collect 99 Books to trigger the bonus game, played with an average bet size from your collected spins.
With a godly 99% RTP and a max payout of 12,070x your stake (up to 1,207,000 credits at max bet), this high-volatility slot promises epic potential worthy of Olympus.
While you can trigger the Book of 99 bonus game by collecting 99 Wilds, you can also trigger it the easier way. You can trigger it by landing 3 or more Wilds, from left to right on adjacent reels, for which you get 10 Free Spins. So essentially, the Wild Collection feature will help you later retrigger the feature, since you’ll need time until you collect 99 Wilds, compared to landing only 3 or more Wilds to first trigger the bonus game.
Before the Free Spins start, the game will select a random symbol to become the special Expanding Symbol, much like in the classing Book of Dead online slot. Land the Expanding Symbol, and it will expand to cover the entire reel it landed on. Land more than one Expanding Symbol, and they will pay both ways, regardless of the lines they landed on, even if the symbols are not connected from left to right.
Book of 99 is an incredibly unique slot, truly worth the try. Its title does remind you of Book of Ra, but the slot is nothing like it. The design does remind you of the old Medusa series of slots. Relax Gaming has done an amazing job with the overall production. Yet, the star of the slot is the 99.00% RTP. This RTP is rarely offered by developers nowadays, so it is quite a refreshment. This 99.00% RTP paired with the 12,070x the stake max payout potential make Book of 99 the it-slot, the slot that could well become the next big thing. You can try it out at one of our best online slot sites for real money!
If you enjoyed Book of 99’s epic Greek vibe, I also recommend Rise of Olympus, Gates of Olympus, and Divine Fortune, three mythic adventures that deliver godly visuals, powerful features, and the same Olympian thrill of chasing legendary wins.
Karolis Matulis is an SEO Content Editor at Casinos.com with more than 6 years of experience in the online gambling industry. Karolis has written and edited dozens of slot and casino reviews and has played and tested thousands of online slot games. So if there's a new slot title coming out soon, you better know it – Karolis has already tried it.
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