One symbol is both wild and scatter, and each free-spins round turns on which symbol expands. How the round works, and the four Book games we review side by side.
In a Book slot, one symbol does two jobs: the Book is both the wild and the scatter, and three or more anywhere on the reels start 10 free spins. Before the round begins, the game picks one ordinary symbol to expand. Whenever enough copies of it land, each one grows to cover its whole reel and pays across those reels, on a line or not. Novomatic’s Book of Ra set the pattern in 2005, Play’n GO’s Book of Dead made it an online staple, and we review four games built on it.
How the Book Feature Works
Outside the feature, a Book game is a plain payline slot. The Book substitutes for other symbols when it helps a line and pays as a scatter wherever it lands, and most classic titles add a card gamble after a base-game win, which either doubles the win or loses it.
The free spins are where the game is decided, and two draws set their value. The first is reaching the round, which on the classic titles happens roughly once in 100 to 200 spins. The second is the symbol chosen to expand. When it lands on enough reels, two or three depending on the symbol, every copy stretches from top to bottom and the win is paid across those reels even when they are not side by side. A top symbol covering all five reels is how these games reach their ceilings; a low card can expand all round and still return little. Three more Books during the round add a further 10 spins with the same symbol, and retriggers have no limit.
The Four Book Slots We Review
| Slot | Studio | Top RTP | Lowest Version | Volatility |
|---|---|---|---|---|
| Book of 99 | Relax Gaming | 99.00% | Single version | Medium to high |
| Legacy of Dead | Play’n GO | 96.58% | 84.55% | High |
| John Hunter and the Book of Tut | Pragmatic Play | 96.50% | 94.50% | High |
| Book of Dead | Play’n GO | 96.21% | 84.18% | High |
Book of Dead
Book of Dead is the game most players picture when they hear “Book slot”, and Play’n GO built it with almost nothing besides the feature: one free-spins round, the optional gamble and a random expanding symbol, all on five reels and 10 lines. The round pays its biggest wins when Rich Wilde, the adventurer, is the symbol drawn. Between the top version and the 84.18% one, Play’n GO also supplies casinos with 94.25%, 91.25% and 87.25%. The studio has returned to ancient Egypt without the book, too: in Ankh of Anubis, every Ankh caught in free spins fills a meter, and five of them bring extra wilds.
Legacy of Dead
Play’n GO’s follow-up arrived in 2020 and keeps its predecessor’s expanding-symbol round, now on 10 fixed lines with the card gamble still in place and a top win of 5,000x the stake. Because the two games play so alike, the real choice between them is which version a casino runs: Legacy of Dead’s ladder has steps at 94.51%, 91.51% and 87.56% on the way down to its lowest.
John Hunter and the Book of Tut
Pragmatic Play’s entry comes from its John Hunter adventure series. It also uses a 5×3 grid with 10 lines, starts free spins on three, four or five scatters and keeps to a single expanding special symbol. Its 5,500x top win is the largest of our four, and Pragmatic places the game at the top of its own volatility scale. A middle version at 95.50% sits between the two figures in the table.
Book of 99
Relax Gaming changed the value rather than the formula. Book of 99 sets the Greek myths on the usual 5×3 reels and adds a meter that collects book symbols, a second way into the free spins alongside the scatter trigger. By Relax’s own figure its top win is 5,000x, and no casino can run it lower than 99.00%, which also puts it in our 99% RTP tier.
How Other Studios Changed the Formula
Nobody owns the Book idea. Megaways has to be licensed from Big Time Gaming, but any studio can build a Book game, so they compete on the twist each one adds.
Novomatic’s own Book of Ra Deluxe, the sequel to the original, stays close to the template and doubles free-spins wins with a 2x multiplier. It returns 95.10%, below the four above, and tops out at 5,000x.
Nolimit City’s Book of Shadows moves furthest from it. Shadow Rows let you play 10, 15 or 20 lines, reels can be locked, and a win can be gambled for free spins rather than cash. The return is 96.01% at three rows and rises slightly with more, volatility is Extreme, and the top win is 30,338x, about six times the ceiling of the classic games.
Pragmatic Play’s Book of the Fallen hands you the choice of expanding symbol before the round, so you trade between a symbol that lands often and pays small and one that lands rarely and pays big. It returns 96.50%, with 95.50% and 94.50% versions, caps at 5,000x and adds a Super Spin Ante Bet. It also ships with a bonus buy, which UK-licensed casinos switch off.
Book Slots or Expanding Wilds
Both features fill a reel with one symbol, which is why they get mixed up, but they work differently. In a Book round the symbol that grows is an ordinary paying symbol picked for that round, and it pays across reels without needing a line. An expanding wild is the wild itself: it stretches over its reel and substitutes to complete normal lines, as it does in NetEnt’s Starburst.
The random pick gives Book games an extra layer of variance, so most of them run high, while expanding-wild games spread from low volatility to high. Ceilings differ too: 5,000x is the usual Book cap with Book of Shadows far beyond it, and expanding-wild games range from a few hundred times the stake to around 12,000x. On a fixed budget an expanding-wild game is more often the steadier ride; a Book game saves more of its return for a rarer, bigger round. Our expanding symbols page covers the wider family.
