Book of Ultimate Infinity: Slot Overview

The next title to take a run at ReelPlay’s Infinity Reels mechanic comes from SG Digital in the Egyptian-themed slot Book of Ultimate Infinity. With the feature proving lucrative for ReelPlay, SG Digital becomes the third studio so far to license it, and they’ve opted to give it a more old-school flavour. Alongside the contemporary reel-expanding system sits a bonus round packed with full-reel expanding symbols selected from a weathered ancient book. It’s essentially ‘Book of’ gameplay dropped into a modern framework—so, does it deliver?

Even if we call it “modern,” the setting is anything but. With this theme you’re almost locked into the familiar scenery: pyramids on the skyline, the Nile nearby, palms, temples—the standard Ancient Egypt package. Soft clouds slide across the background, while an Arabian-leaning soundtrack ties the presentation together. It looks bright and inviting, though it’s not exactly new territory.

Book of Ultimate Infinity runs smoothly on any device, with stakes ranging from 20 p/c to $/€50 per spin. It’s also a slot that asks for persistence before it shows its best side, as landing free spins can take some effort through stretches of sandstorm-like dead spins. The volatility has a brooding feel—there are moments where it sparks into life—and the overall potential is respectable. The RTP on 96.5% is solid too, sitting comfortably above the norm.

Each spin begins with 3 reels showing 4 symbols per reel. If at least 3 matching symbols appear on reels 1, 2, and 3, an extra reel is appended to give you another shot at improving the result. This keeps going as long as the newest rightmost reel increases the win. That, in short, is the Infinity Reels concept. For the record, the reels are capped at 50, so “infinity” has its limits. When the first additional reel arrives, a x2 win multiplier is applied, then it rises by +1 for every further reel added.

A payout is created when at least 5 matching symbols connect starting from reel one. Your return is calculated as the number of symbols in the combination multiplied by that symbol’s value. At the bottom are the J-A royals, then come knives, Ankhs, a queen, a gold statue, and a pharaoh. The higher-value picture symbols pay 0.10 to 0.25x the bet per symbol, meaning a five-of-a-kind returns 0.5 – 1.25 times the stake. Note that multipliers and longer reel runs can lift those numbers from time to time. Supporting the hit rate is a wild that doesn’t look particularly Egyptian, and it substitutes for everything except the Gold Book and the special Expanding Symbols.

Book of Ultimate Infinity: Slot Features

Beyond Infinity Reels, the game also includes free spins activated via the Gold Book scatter. The trigger method is a little different: at the start of every spin, a reel (from 6 to 15) is randomly chosen to be the one that can hold the Gold Book. If your reel expansion during a winning sequence reaches that selected reel, you receive 10 free spins. Put simply, the reels must extend to at least 6 before the bonus can even be in play.

When free spins begin, one symbol is randomly selected as the special expanding symbol. If you retrigger free spins, that chosen symbol does not change. Hitting a special symbol or a book on the rightmost reel always adds another reel, even if the win doesn’t improve. In classic ‘book’ fashion, once 2 or more reels show the expanding symbol, they expand to cover all positions and pay whether or not they land next to each other.

Book of Ultimate Infinity: Slot Verdict

To borrow the spirit of a Bill Hicks line, just as evolution didn’t stop when humans grew thumbs, SG Digital suggests there’s still room for ‘book of’ slots to evolve. In that sense, Book of Ultimate Infinity highlights how adaptable ReelPlay’s framework really is. We’ve already had straightforward takes, in-game jackpot versions, Megaways, and now a Book of Ra-style spin on it. Could we be on the verge of a wave of refreshed classics? With studios like SG Digital involved, it’s easy to imagine the doors swinging wide open.

That said, Book of Ultimate Infinity carries over familiar issues from earlier versions. The window dressing changes, but the central loop—the grind—remains much the same. And it can be a real grind too, with plenty of empty spins broken up by the occasional bigger hit. You’ll sometimes build a long multi-reel win with a chunky multiplier, only to wonder why the payout still feels underwhelming once it lands. It also feels a bit odd not having Megaways here, which previously injected extra unpredictability into a base game that can drift toward repetitive.

A neat detail is the map beneath the reels that expands and contracts to show where the triggering scatter sits. Because the scatter’s position moves, it adds a touch of suspense—you never quite know where it’s going to be. Once the feature finally lands, Book of Ultimate Infinity clicks more and starts to stand apart from other entries using the mechanic. It’s also the point where players can realistically chase the maximum payout, which is capped at $/€250k. Still, the low symbol values can be restrictive, since even large stacks of the chosen symbol may not amount to much.

Book of Ultimate Infinity doesn’t reach the genre’s top tier like Book of Dead, but anyone who enjoys Infinity Reels or expanding special symbols may find it worthwhile. Overall, SG Digital has made good use of the mechanic and introduced a feature we haven’t really seen in these games before, helping it stand out as one of the stronger Infinity Reels releases in a while.

Don’t Miss

If you’re looking to try more slots that use the Infinity Reels mechanic, we recommend Relax Gaming’s leprechaun-themed title Emerald’s Infinity Reels. As another option, Red Tiger offers a comparable engine called InfiniReels, with Dragon’s Fire InfiniReels being a standout example.