Book of Ultimate Infinity

Book of Ultimate Infinity Slot Review – What to Know Before You Spin

Book of Ultimate Infinity is a hybrid “Book-style” slot that bolts expanding special symbols onto an Infinity Reels–style extending grid. It takes the familiar high-risk “Book of…” free spins format and stretches it sideways with potentially endless extra reels and multiplying wins.

Right from the first few spins, it’s clear this one is aimed at players who like dangerous maths and aren’t afraid of long dry spells if the upside is high enough:

• Fans of Book of Ra / Book of Dead–style games who want something less static.
• High-volatility hunters chasing single big hits rather than steady grind.
• Feature chasers who enjoy escalating mechanics, multipliers, and expanding grids.

Key facts at a glance:

• Provider: SG Digital / Light & Wonder (ReelPlay Infinity framework).
• Release: 2020.
• Volatility: Very high.
• RTP: Around 96% at the default setting (casino-dependent).
• Max win potential: Up to roughly 25,000x stake in theory.
• Core mechanics: Extending reels with Infinity-style respins + Book free spins with expanding symbol.

In practice, that translates into a volatile, swingy experience. The pace feels measured on dead spins, but once the Infinity mechanic starts firing and multipliers climb, the screen can go from quiet to chaotic in a handful of spins. It’s a slot that can punish for long stretches and then suddenly explode, which is exactly what many high-risk players are looking for.

Theme, Setting & Visual Atmosphere

Overall Theme and Story Angle

The theme leans into the “mystic tome” idea without tying itself too tightly to any one culture. There are clear Egyptian touches in the symbols and background, but it’s not a straight copy of Book of Ra. Instead, it comes across as a slightly more modern, stylised trip into a forgotten temple with a hint of fantasy rather than strict historical detail.

The setting is a stone chamber bathed in warm gold and amber hues. Pillars flank the reels, and the mysterious Book symbol glows with the kind of soft, pulsing light that quietly signals “this is important”. There’s a sense of dusty age, but the interface and animations feel clean and contemporary rather than old-fashioned.

Compared with traditional “Book of…” slots that sit rigidly on a 5x3 grid, this one looks more open and elastic. The Infinity mechanic is hinted at visually: there’s empty space to the right of the starting reels, and the whole frame feels like it could stretch into the darkness. It subtly tells you the game doesn’t stop at five reels; the room, like the grid, feels as if it could keep going.

On load, the color palette is mostly gold, brown, and deep blue. Nothing screams for attention. There’s enough ornamentation to sell the theme, but the screen doesn’t feel cluttered. The layout leaves space for the extending reels animation and win readouts, so even when the grid grows, it stays readable and doesn’t turn into a blur of symbols.

Visual Design and Reel Layout

At the start of each spin, the layout looks quite conventional:

• 3 reels visible.
• 4 rows high.

That’s intentionally tight. The real action only begins when you land a win on the rightmost reel. When that happens, a new reel slides in from the right, the win is recalculated with the new reel in play, and your total win multiplier ticks up. This repeats as long as each new reel extends the winning combination.

The animation is smooth rather than flashy. The camera doesn’t zoom; the frame simply stretches sideways, and the new column slots into place with a solid mechanical thunk. After a few consecutive extensions, the grid feels long, almost like a scroll unrolling across the table. There’s a clear sense of escalation without losing track of individual symbols.

Symbol animation is restrained. Wins highlight with a soft glow and a brief shimmer; premium symbols might pulse or tilt slightly when part of a winning combo. The game doesn’t resort to constant explosions or strobe effects, which helps on longer sessions when aggressive visuals can become tiring.

The interface follows the usual SG / ReelPlay layout:

• Spin button on the right, large enough to be easy to tap on mobile.
• Bet controls grouped on the left or bottom, depending on device orientation.
• Balance, total win, and stake displayed clearly along the bottom bar.

When the reels extend, the UI stays anchored, so your eyes don’t have to chase information around the screen. It feels stable even as the grid is stretching out, and the important numbers remain where you expect them to be.

Sound Design and Pacing

The soundtrack leans into atmospheric mysticism. Low, droning pads sit under subtle chimes and the occasional hint of Middle Eastern scales, without pushing too hard into cliché territory. It’s more of an ambient bed than a melody, designed to fade into the background after a few minutes and not wear you down.

Each spin has a light mechanical sound: a soft whirr on start, a slightly staggered stop across the reels. Wins are marked by a clean, ascending tone that grows in intensity as the multipliers climb. When the grid extends, there’s a distinct sliding sound paired with a bassy thud as the new reel locks in, which does a lot to sell the feeling of momentum and weight.

Special events have their own audio cues:

• Landing the Book symbol adds a more pronounced chime.
• Two Books on screen bring in a subtle “tease” swell.
• Triggering free spins or hitting a big extension sequence ramps up the backing track, layering extra percussion and brighter tones.

There’s a standard speaker icon for muting, usually tucked near the menu button. The game remains playable and legible without sound; the visual cues for extensions, multipliers, and Book hits are strong enough. That said, the Infinity mechanic is noticeably flatter in silence, because so much of the tension is carried by those rising audio layers when the reels keep stretching.

Symbols and Paytable Structure

Low-Paying Symbols

The low-tier symbols follow the familiar deck-rank pattern:

• 10, J, Q, K, and A.

They’re rendered in a stylised stone or gold script, often framed with simple decorative flourishes. Colors are vivid but not neon—deep reds, greens, and blues for the royals against the warm background. Over a long session, that bit of restraint helps the set feel readable rather than garish.

These ranks appear frequently, and they’re what keep the reels feeling active between more meaningful hits. Typical small wins fall into the “get a fraction of your bet back” range: a few credits here and there, occasionally a small profit on a single spin if you connect them across extended reels.

What matters more than raw payout on these is how they interact with the Infinity mechanic. Because wins are evaluated with each new reel that extends, low-symbol combos can drag out across a surprising number of columns. A line of Qs or Ks that keeps picking up new matching symbols can turn a nothing-looking spin into a respectable return, especially with the growing multiplier.

Still, in real play, the lows serve mainly as drip-feed:

• They smooth out variance slightly during dry stretches.
• They contribute to moderate extension runs that set up the occasional better premium hit.

You won’t be chasing them, but you’ll notice when they form those long, slightly unexpected chains.

High-Paying Symbols

The premium set is where the theme comes into focus. Symbols typically include:

• A scarab beetle gleaming with turquoise and gold.
• An ankh or similar sacred relic.
• A robed priest or high-ranking figure.
• The top symbol: a dramatic deity or adventurer, depending on the version.

Each premium is more intricately designed than the royals, with sharp highlights and rich colors. On the darker reel background, they stand out clearly when they drop in clusters. When part of a win, they tend to get a brief halo or glow, with subtle particle effects that appear and fade quickly.

At base bet, three-of-a-kind premiums already beat most low-symbol hits. Stretch them across more reels and the value ramps up quickly. The top symbol is calibrated so that a long, extended combo can deliver serious money, especially when paired with a high extension multiplier.

Full-screen or near-full-reel combos of premiums across many reels are theoretically possible thanks to the Infinity mechanic, but in practice they’re rare. More common are:

• 4–7 reel chains of the mid-tier premiums.
• Occasional extended runs of the top symbol that land just enough matches to feel significant.

Once the reels start extending and the multiplier climbs, any premium on that right edge starts to feel important. It’s easy to find yourself watching that last position, hoping the top symbol drops in to latch onto the growing chain.

The Book Symbol – Wild, Scatter, and Special Role

The Book symbol is the centerpiece. It’s a thick, golden-edged tome with glowing glyphs and a subtle magical aura, often sitting slightly angled as if about to open. On landing, it tends to emit a soft pulse of light that helps it stand out in the grid.

It plays a dual role:

• Wild: It substitutes for all regular symbols to complete winning combinations.
• Scatter / Bonus trigger: A set number of Books on screen (commonly 3 or more) activates the free spins feature.

In the base game, hitting two Books feels like a proper tease. The reels slow a fraction as the third potential Book position stops, and the audio lifts into a more urgent pitch. The symbol might also “shimmer” for a beat longer than other icons when it lands, drawing the eye toward potential triggers.

The Book usually has its own paytable value as well, paying a modest amount for 3+ of a kind. These wins rarely drive a session by themselves, but they add a little consolation when you land multiple Books without triggering the bonus – at least there’s something back.

When you do trigger free spins, the Book animation becomes more pronounced: the symbol opens, pages flicker with light, and the screen transitions into the bonus selection sequence. There’s a satisfying weight to the way it’s handled, which fits its central importance to the slot.

Paylines, Ways, or Infinity Mechanic

Unlike classic Book slots that use fixed paylines, Book of Ultimate Infinity uses an Infinity Reels–style system. You start with 3 reels, and any win that touches the rightmost reel triggers an extension.

Mechanically, it works like this:

1. Spin starts on a 3x4 grid.
2. If a winning combination includes a symbol on the rightmost reel, the game adds a new reel to the right.
3. The win is recalculated with the new reel included.
4. A global win multiplier increases (often +1) for each reel extension.
5. Steps 2–4 repeat as long as the new rightmost reel continues the win.

There may be a practical upper limit coded in (some Infinity games cap at a very high reel count), but for everyday play it feels open-ended. Reaching very long extensions is rare, so the “infinite” idea mostly serves as a tension-building device rather than a regular outcome.

From a player’s perspective, a strong setup usually means:

• A winning combo that includes the rightmost reel.
• A mix of premiums already in place before the extension sequence begins.
• Any spin where the grid has extended 4+ times and the multiplier is clearly climbing.

Once you’ve seen a few spins, it becomes intuitive. If the right edge keeps matching, you’re in business; if it doesn’t, the sequence stops. It’s less about memorising paylines and more about watching that right side of the screen.

Math Model – RTP, Volatility and Hit Frequency

RTP Values and Versions

The default theoretical RTP of Book of Ultimate Infinity sits close to 96%, broadly in line with other high-volatility, feature-rich slots in this space. That’s an acceptable level for long-term value, especially given the ceiling on potential payouts.

Like many modern online slots, it may come with multiple RTP configurations that casinos can select. Some sites might run it at slightly lower settings (e.g., 94% or 95%), which subtly increases the house edge. This doesn’t change the feel of individual sessions much, but it does matter over the long haul.

To check the exact RTP where you’re playing:

• Open the game’s menu, usually via a small “i” or hamburger icon.
• Look for a “Help”, “Rules”, or “Paytable” section.
• RTP is typically listed near the top or at the end of the technical details.

It’s worth a quick glance before committing, especially if you’re planning a longer session or playing at higher stakes.

Volatility Profile

This is a very high variance slot. That label isn’t just marketing language—it shows up clearly in how the game behaves.

In real terms, you can expect:

• Long neutral or losing patches with frequent dead spins.
• Many wins that don’t cover your full bet, especially from the low-tier symbols.
• Occasional medium hits from moderate extension sequences.
• Rare but substantial spikes when the reels stretch and premiums align.

A typical session tends to look like this: a lot of small, forgettable spins where the grid stays at 3–4 reels, occasionally broken by a burst of action when an extension run starts. Most of those bursts will fizzle after a couple of new reels, returning something close to your stake. Every now and then, though, the right edge keeps matching, the multiplier climbs past x4, x5, x6, and you can feel the math model flex.

Bonus rounds follow the same pattern. Many will underwhelm. A few will deliver the kind of single feature that defines the entire session.

The profile suits players who:

• Are comfortable with volatility and bankroll swings.
• Are chasing a big outcome rather than consistent small wins.
• Don’t mind stretches with little to show if it means the ceiling remains high.

Base Game Flow and Reel Extension Dynamics

In the base game, every spin is a small gamble on whether the Infinity mechanic kicks in. With only 3 reels to start, plenty of spins end without drama. Wins tend to become interesting only when they touch that rightmost column.

When they do, the flow is distinctive:

• First extension: feels like a “nudge” – maybe this spin is going somewhere.
• Second and third: the screen starts to look stretched, and the multiplier is already turning even small symbol chains into decent returns.
• Fourth and beyond: adrenaline territory; each new reel feels like it might either break the chain or tip it into something memorable.

Because win evaluation is repeated after each new reel, you often watch your total win counter tick up in steps. That staircase effect, combined with the growing multiplier, creates a sense of watching a result build rather than just pop in fully formed.

The base game, on its own, can be quite punishing. Without the free spins, it relies heavily on those rare deep extensions to generate big wins. For most players, that makes the bonus round feel essential to the long-term excitement rather than just a nice extra.

Free Spins and Book Feature

Triggering the Free Spins

Free spins are triggered by landing a set of Book symbols anywhere on the reels in a single spin, typically three or more. Because the grid can extend, there’s an interesting quirk: Books on newly added reels can count toward the trigger as long as they appear during the extension sequence.

That leads to occasional moments where:

• Two Books land on the initial 3 reels.
• A win triggers an extension.
• A third Book arrives on the new reel, turning what looked like a near-miss into a bonus round.

The audio and visuals lean into these situations. Each Book that lands during a spin adds tension, with the third one causing a brief pause before the game transitions into the feature.

Choosing / Assigning the Expanding Symbol

Once free spins trigger, the Book performs its classic “Book slot” role: it selects a special expanding symbol.

The process usually goes as follows:

1. The reels fade slightly.
2. Symbols flip through in a quick animation, like a mini wheel.
3. One regular symbol is chosen to act as the special expander during the bonus.

If a premium is chosen, the feature becomes high-risk, high-reward: harder to land, but worth far more when it does. If a low-paying rank is selected, expansions will be more frequent, offering steadier but usually smaller payouts. Both setups have their own kind of appeal, depending on how you like your volatility.

The chosen symbol is clearly marked on screen throughout the bonus, usually highlighted on the paytable panel or with a glowing frame whenever it lands.

How Expanding Symbols Work with Infinity Reels

This is where Book of Ultimate Infinity diverges from standard Book slots in a meaningful way.

In many Book games, when the chosen symbol can form a winning combination during free spins, it expands vertically to fill its entire reel, paying as if on all paylines. Here, that idea meets the extending grid mechanic.

Broadly, the logic is:

• If enough instances of the chosen symbol land to count as a win, they expand across their reels.
• Those expanded reels then interact with the Infinity mechanic, potentially triggering extensions if the rightmost expanded reel forms part of a winning combo.
• Each new reel added can contain more copies of the chosen symbol, feeding into both the expansion and the multiplier.

The result is a bonus round that can snowball quickly. A single free spin where the special symbol hits heavily across multiple columns can push the grid far out to the right, with an escalating multiplier turning a decent setup into a serious hit.

Of course, the opposite happens too: you can go multiple free spins with few or no appearances of the chosen symbol, especially if it’s a premium. Those dead bonus rounds are baked into the volatility and shouldn’t come as a surprise.

Number of Free Spins and Retriggers

The initial number of free spins is typically modest—often 10. That’s standard for Book-style games and is balanced around the power of the expanding feature.

Retriggers are usually available by landing another set of Book symbols during the bonus. When that happens, you’re awarded extra spins, and the existing expanding symbol choice stays active. That continuity is important: a bonus that starts slow can still turn around if you hit a retrigger and finally connect a big expansion.

Retriggers aren’t common, but when they land, they often transform a mediocre feature into something memorable, especially if the grid and multiplier have already shown signs of life.

Multipliers, Max Win, and Realistic Outcomes

Every time the reels extend during a single spin, a global win multiplier ticks up by 1 (or in a similar small step). This multiplier applies to the total win from that spin, not just the incremental extension, so long runs can feel explosive.

In the base game, a sequence of 4–6 extensions might push the multiplier into the x5–x7 range, turning an otherwise average line of premiums into a solid payout. In free spins, where expanding symbols and retriggers can keep a spin alive longer, that multiplier has more room to climb.

The theoretical max win is pitched in the ballpark of 25,000x your stake. That number assumes a best-case scenario:

• Deep reel extensions.
• High multipliers.
• Strong presence of the top premium as the expanding symbol.
• Possibly multiple retriggers.

Realistically, most “good” hits fall far lower than that ceiling. Strong outcomes that players actually see tend to cluster around:

• 50x–200x stake for solid base-game extensions.
• 100x–500x stake for decent free spins with some expansion action.
• Bigger outliers when everything lines up, but those are rare and can take many sessions to see.

Understanding that gap between theoretical max and everyday results is key. The game is built to allow huge wins, but it doesn’t hand them out freely.

Betting Range, Bankroll Management and Session Planning

Most implementations of Book of Ultimate Infinity cover a broad betting range, suitable for low-stakes grinders and high-rollers alike. Exact limits depend on the casino, but you often see something like:

• Minimum bet around €0.10–€0.20 per spin.
• Maximum bet reaching €50–€100 per spin.

Given the extreme volatility, how you approach stake sizing matters more than on gentler slots.

A few practical guidelines:

• Think in terms of 200+ spins. On a game with this kind of variance, a meaningful session often stretches over a few hundred spins. Choose a stake that lets your bankroll comfortably absorb that.
• Expect streakiness. It’s normal to go 50–100 spins with only small wins and no bonus. Plan your budget with that in mind.
• Downshift if frustrated. If the reels are cold but you don’t want to quit, dropping the bet size can extend your session without increasing pressure.

This is not the ideal game for someone trying to turn a small, short bankroll into quick profit. It’s better suited to players who can accept dry runs while chasing that one strong feature or extension sequence.

Mobile Experience and Technical Performance

On mobile, Book of Ultimate Infinity holds up well. The Infinity mechanic is naturally horizontal, and the developers have designed the interface so that extended reels remain legible even on smaller screens.

Key points:

• The 3x4 starting grid is compact, leaving room for buttons and information bars without feeling cramped.
• As reels extend, the game slightly shrinks the symbol area and may introduce subtle scrolling or compression, but not to the point where symbols become indistinct.
• Touch controls are responsive; the spin button is large enough to avoid mis-taps, even in portrait mode.

Because the slot relies on animations for reel extensions and symbol expansions, a stable connection helps. On weaker devices or slow networks, there might be slight pauses when the grid grows, but the core gameplay is intact. Most casinos allow lowering graphics quality in settings if needed.

Muted play on mobile, whether on a commute or late at night, still feels coherent thanks to strong visual feedback: expanding books, growing multipliers, and reel extension indicators make it clear what’s happening even in silence.

Who Will Enjoy Book of Ultimate Infinity?

This is not a gentle, low-stakes timewaster. It’s designed for a specific type of player.

It suits:

• Book slot enthusiasts who enjoy the expanding symbol mechanic but feel bored with static 5x3 grids.
• High-volatility fans who are happy to ride through lean spells in pursuit of rare, significant hits.
• Mechanic-focused players who like watching a system build—reels stretching, multipliers ticking up, symbols expanding—instead of just static line wins.

It’s less ideal for:

• Those who prefer frequent medium wins and long, steady sessions with minimal swings.
• Players who dislike the feeling of “nothing happening” through extended runs of dead spins.
• Anyone uncomfortable with the idea of a bonus round that can sometimes return very little.

Approached with the right expectations and a bankroll sized for its swings, it can feel tense, occasionally brutal, but undeniably engaging.

Final Thoughts on Book of Ultimate Infinity

Book of Ultimate Infinity takes the familiar Book-style expanding symbol free spins and fuses them with an Infinity Reels–style extending grid and growing multipliers. The result is a volatile, high-ceiling slot where the screen can sit quiet for long stretches and then suddenly lurch into life as reels stretch, books expand, and win multipliers climb.

For the right audience—players who understand and embrace that kind of risk—the combination offers a fresh spin on the “Book of…” formula without discarding what made it compelling in the first place.