Book of 99 delivers a groundbreaking 99.00% theoretical return to player, substantially higher than the industry standard of 94-96%. This means that for every hundred units wagered, the game theoretically returns ninety-nine units over the long term, giving players exceptional value and extended gameplay sessions on the ancient Greek reels.
Every wild Book symbol that lands during base game spins adds to your collection meter. Once you gather all ninety-nine golden books, you trigger free spins at the weighted average bet of your collection journey.
The ornate golden book serves dual functions: it substitutes for all regular symbols to complete winning combinations across the ten paylines, and each appearance in the base game increments your collection meter. Book of Souls slot employs a similar wild substitution mechanic alongside its RESPIN feature that progressively expands the grid from 5 reels to deliver up to 32,768 ways to win.
Dual FunctionTrigger ten free spins either by landing three or more Book wilds in a single spin, or by completing the collection of ninety-nine wilds. One of the nine regular symbols is randomly chosen as a special expanding symbol for the entire feature.
10 Spins AwardedDuring free spins, if two high-value symbols or three low-value symbols of the chosen special type land anywhere on the reels, they expand to fill entire columns and pay on all ten lines regardless of their horizontal position.
High Value: 2+ Symbols Low Value: 3+ SymbolsBook of 99 stands apart in the crowded Greek mythology slot market through its innovative collection mechanic and industry-leading return to player. The journey to ninety-nine wilds creates genuine anticipation across sessions, while the dual trigger system for free spins ensures frequent feature activation. The expanding symbol mechanic during free spins can deliver substantial wins when high-value characters fill multiple reels.
Use the minus and plus buttons flanking the bet display to select your wager per spin. The game always plays all ten paylines. Rich Wilde and the Book of Dead by Play'n GO also features 10 fixed paylines that remain active across all bet levels.
Press the large circular spin button in the centre of the control bar to set the five reels in motion across three rows.
Hit a win by landing three or more matching symbols across any of the ten paylines — each one read from left to right, beginning at the leftmost reel.
Each golden Book wild that appears increments the collection meter visible on the left side. Track your progress toward the ninety-nine target.
Activate the bonus by landing three or more Book wilds in one spin, or by filling the collection meter to ninety-nine.
During ten free spins, the randomly selected special symbol expands across full reels when sufficient instances appear, paying on all lines.
The 99.00% return to player rate is exceptionally high for online slots. Most games range from 94% to 96%, meaning Book of 99 theoretically returns three to five percentage points more to players over the long term. This translates to extended gameplay and better value from your bankroll.
Every time a golden Book wild symbol lands anywhere on the five-by-three grid during base game spins, it adds one unit to your collection meter displayed on the left side of the screen. The meter tracks from zero to ninety-nine. When you reach ninety-nine collected wilds, you automatically trigger ten free spins. The collection persists across sessions until triggered.
First, you can trigger ten free spins immediately by landing three or more Book wild symbols anywhere on the reels in a single spin. Second, you activate the feature by collecting ninety-nine Book wilds over time through the collection meter. Both methods award ten free spins with a randomly selected expanding symbol. Book of Ra Deluxe awards its ten free spins exclusively through scatter landing, requiring three or more book symbols in a single spin without any collection meter alternative.
When your free spins kick off, the game randomly selects one of the nine standard symbols to become your special expanding symbol. Throughout each free spin, landing just two or more high-value expanding symbols anywhere on the reels (or three or more for low-value symbols) triggers an exciting expansion that fills their entire reels. These expanded symbols then deliver wins across all ten paylines no matter where they land, completely breaking free from the usual left-to-right rules.
Yes. If three or more Book wild symbols land anywhere during your free spins feature, you receive an additional ten free spins. The same expanding symbol continues throughout the retriggered spins. You can retrigger multiple times within the same feature.
Hit ninety-nine collected wilds and you'll unlock free spins played at the weighted average of every bet you placed while collecting them. That average is then rounded to the nearest valid bet multiple using stochastic rounding. Prefer the fast track? Land three or more wilds in a single spin, and your free spins will use the bet from that triggering spin.
Relax Gaming is a B2B supplier delivering high-quality online casino content to operators globally. Established in 2010, the Malta-based studio has built a reputation for innovative mechanics and player-focused design. The company's portfolio spans diverse themes beyond Egyptian exploration, including ancient Mesoamerican civilizations featuring comparable bonusspin structures with expanding symbol mechanics across ten paylines.
Book of 99 represents their commitment to transparency and value, featuring certified random number generation and the verified 99.00% return to player rate. The game is licensed and regulated for fair play across multiple jurisdictions.
Book of 99 is a game of chance, pure and simple. Its 99% RTP beats most slots, but that figure reflects theoretical returns over the long haul, not what will happen in any single session. Stay in control by setting deposit limits, stepping away regularly, and only wagering what you can comfortably afford to lose. If gambling ever starts to feel like a problem, reach out to organisations such as GamCare or BeGambleAware for support. Players must be eighteen years or older.
Whilst the 99% return sounds attractive, remember this is calculated over millions of spins. Set a strict session budget and stick to it—short sessions can swing wildly either way. The high RTP doesn't eliminate variance; it simply means the house edge is smaller than most slots.
The expanding symbol mechanic during free spins is where the big wins happen. Patience is key—the feature can be elusive. When you do trigger it, the chosen expanding symbol pays on any position across the reels, so landing a high-value expander makes all the difference.
The card gamble lets you double wins, but it's pure 50/50 chance with no skill involved. Using it repeatedly after a decent win is how many players give back their profits. If you choose to gamble, set a limit—perhaps one or two attempts maximum—then collect.
Book of 99 accepts a range of bet sizes, but with high volatility you'll face dry spells between features. Lower stakes extend playtime and give more chances to hit the bonus round. Chasing losses with bigger bets rarely ends well, especially on a game this swingy.
Finally a slot that doesn't rinse you in ten minutes. The 99% RTP actually feels real—I've had sessions where I break even or come out slightly ahead. Free spins can take ages to land but when they do, especially with a decent expander, the payouts are proper. Worth the wait.
Good RTP, decent features, but prepare for patience. Base game is dull and bonuses are rare. When they hit, though, it pays well. Better value than most slots I've tried.
Mixed feelings. The high RTP is nice in theory but I've still lost more than I've won. Free spins are few and far between, and half the time the expander is rubbish. Decent for a casual spin but nothing special.
Absolute bore.
Book of 99 suits players who value a genuinely high RTP and don't mind waiting through lean spells for the free spins feature. The Greek mythology theme is well executed without being overcomplicated, and the 99% return—rare for slots—gives you marginally better long-term value than most alternatives. It's a solid choice for patient, budget-conscious players who understand that even 99% RTP still means the house wins over time.
Watch out for the high volatility, which can drain your bankroll quickly between bonus rounds. The base game offers little in the way of frequent small wins, so sessions can feel flat if free spins don't land. The gamble feature is tempting but risky; many players find it eats into their winnings. Always play within your means, set loss limits, and remember that 18+ responsible gambling applies. This is entertainment, not income.
No. The 99% return to player is a statistical average calculated over millions of spins. Individual sessions will vary wildly due to the game's high volatility—you might win big, break even, or lose your stake quickly. RTP indicates long-term performance, not short-term results.
Free spins frequency varies by session due to the game's volatility, but many players report it feeling less frequent than lower-variance slots. There's no fixed rate—it's determined by random number generation. Patience and bankroll management are essential, as dry spells between features can be lengthy.
The gamble feature is purely optional and offers a 50/50 chance to double your win by guessing card colour. It's high risk—you can lose everything you've just won. If you choose to gamble, set a strict limit (one or two attempts) and collect afterwards. Many players avoid it entirely to preserve their winnings.
