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.
