Book of Fusion: Slot Overview

When you start looking into fusion technology, the potential benefits are mind-blowing. Instead of nuclear fission, which splits atoms to generate energy, fusion forces atoms to combine into heavier ones, releasing energy in the process. The UK Atomic Energy Authority notes that 1 kilogram of fusion fuel could deliver approximately the same amount of energy as 10 million kilograms of fossil fuel. It creates no carbon emissions, and the fusion reaction produces zero radioactive material. Fusion is the process that powers stars, and recreating it on Earth involves heating hydrogen gases to more than 100 million degrees to create plasma, allowing nuclei to merge.

It’s compelling science—and until fusion reactors are commonplace and we’re topping up our phones the way stars illuminate the cosmos, we can pass the time with online slots like Book of Fusion from Light & Wonder, formally SG Digital. True to its title, Book of Fusion joins the long-running family of “book” slots that kicked off years ago with Book of Ra. This time, though, you’re nowhere near the scorching sands of Ancient Egypt; instead, you’re dropped into a scientist’s workshop where the “fusioning” happens. It may not look like the kind of lab where reality and sci-fi collide, but the room is cluttered with mysterious devices and odd contraptions—interesting enough to warrant a closer look.

To get started, players choose a stake from 10 p/c to $/€35 per spin, or they can press the Buy Pass button to jump straight into the bonus round, where available. In standard play, the return to player is 95.97%, nudging up slightly to 95.98% when purchasing free spins. Be aware that lower RTP versions may exist depending on the region, and volatility sits in the medium/high bracket.

In terms of gameplay, Book of Fusion sticks to the familiar blueprint: 5-reels, 3-rows, and 10 paylines. Regular wins begin from the left of the reels, with matching symbols paying left to right along a payline. The 10-A card royals return 10-15x the bet for five of a kind, while five magnets, switches, meters, a not-so-easy-to-name gadget, and the scientist (the top symbol) pay 75-500x the stake.

Book of Fusion: Slot Features

If you’ve played this type of slot before, you’ll already know the book symbol is the key. That’s because the book is wild, meaning it can replace any regular paying symbol as well as the scatter. When 3, 4, or 5 book symbols appear on the reels, they pay 2x, 20x, and 200x the bet, respectively, and also trigger 10 free spins.

Before the free spins kick off, the book opens and chooses 2 pay symbols. The rules don’t spell it out, but it seems to pick one lower-value and one higher-value symbol. These are turned into special expanding symbols. Whenever they form a win during free spins, they expand to cover all positions on their respective reels and pay across all lines. They also pay from any position, so the full-reel symbols don’t need to sit next to each other or begin from the far-left reel. If 3 or more scatters land in the feature, you receive +10 additional free spins, and 2 more pay symbols are randomly chosen to become expanding symbols too. Once all ten symbols are expanders, free spins can no longer be retriggered.

If you’d rather skip straight to the more thrilling stage of the experiment—and the option is offered—you can purchase free spins for 70x the base bet.

Book of Fusion: Slot Verdict

Considering how long Light & Wonder/SG Digital has been producing online slots, it may come as a surprise that Book of Fusion is the studio’s first “book” title. Over the years, the developer has explored a huge range of themes while avoiding a direct attempt at this massively popular format. Even with countless similar slots already available, there’s clearly something about the style that keeps inspiring new entries. To Light & Wonder’s credit, they’ve taken a slightly unconventional route with both the theme and the feature set. It’s not a total reinvention, but the changes do count as a genuine twist.

These games began in Ancient Egypt, and there are plenty of strong choices in that setting—but there are so many that it’s refreshing to step somewhere different. The science theme not only stands out, it also gives room for crackling electricity effects and striking visuals. It evoked the vibe of Pragmatic Play’s The Wild Machine or Skywind Group’s Alive! Megaways, only presented in a “book of” framework, which isn’t something you encounter often. Another rarity is being given two expanding symbols at once rather than the usual single pick. Play’n GO’s Legacy of Dead introduced the concept of adding more expanding symbols on retriggers, but again, it did so one at a time—not two at once like you get here.

Perhaps at some point developers will run out of fresh angles to add to this formula. Until that day, it’s worth acknowledging the studios that still manage to find new variations. Book of Fusion isn’t as world-changing as fusion power becoming widely available, and it doesn’t carry the same sense of gravitas that comes with millennia of Egyptian lore. Still, its differences should make it appealing to “book of” fans looking for something that isn’t commonly found elsewhere.