Every major "Book of" slot ranked by RTP and max win — Book of Dead, Book of Ra, Legacy of Dead, Book of 99, Book of Shadows, and more — the expanding-symbol mechanic that defines the whole format, and exactly which 2005 release actually started it

"Book of" has become one of the most recognisable slot naming conventions in the industry — a genuine sub-genre built around a single shared mechanic (and, less charitably, a title format other studios have leaned on heavily because of how well the original performed). This guide ranks the major "Book of" titles by RTP and max win, explains the expanding-symbol mechanic that defines the format, and traces it back to the specific 2005 release that started the whole thing.

Where the "Book of" Format Actually Began

Novomatic's Book of Ra, released in 2005, is the title that originated the format — initially a land-based casino success before becoming what's widely described as an overnight hit once brought online, and the direct template every subsequent "Book of" title has built on since. The core mechanic it introduced: a symbol is chosen randomly at the start of a bonus round (or, on some titles, at any point during play), becoming a special expanding symbol — when that symbol lands during free spins, it expands to cover the entire reel it appears on, dramatically increasing the number of winning combinations that spin can produce. This is the single defining feature that separates a genuine "Book of" title from a slot that simply shares similar Egyptian or ancient-adventure theming without the mechanic itself.

Best "Book of" Slots, Ranked by RTP

†Book of Atem: WowPot!'s RTP runs lower because it's a progressive jackpot title — a portion of every stake feeds its jackpot pool rather than the base game's own payout structure, the same trade-off covered in detail in this site's Progressive Jackpot Slots guide, where this exact title holds the UK's largest documented online progressive jackpot win on record (£15,183,085, April 2021).

Book of 99's headline 99% RTP is genuinely the highest of any title on this list by a considerable margin — worth cross-referencing against this site's Best Payout / Highest RTP Slots guide, which covers the small handful of slots across the entire market (not just "Book of" titles) that reach this RTP tier. Book of Duat and Book of Shadows carry the largest max win figures here (32,760x and 30,338x respectively), considerably above the 5,000x ceiling common to several of the format's older or more conservative entries.

What Makes a Title Genuinely a "Book of" Slot

The theming alone doesn't qualify a title as part of this format — plenty of Egyptian- or ancient-adventure-themed slots exist without using the expanding-symbol mechanic that actually defines "Book of" as a category. The genuine test is the mechanic itself: a randomly-selected symbol that becomes a full-reel expanding wild-equivalent during a bonus round, retriggerable in most titles by landing further scatter symbols during that same bonus. Titles that share the theme but not the mechanic — a broader Egyptian-themed slot with a standard scatter-triggered free spins round and no expanding-symbol feature, for instance — sit outside this specific format even if they're visually similar.

How the Bonus Round Actually Works, Step by Step

Using Book of Dead as the worked example — the mechanics are near-identical across almost every "Book of" title, given how closely the format has been followed since Book of Ra's original release.

Landing three or more scatter symbols anywhere on the reels triggers the bonus round, awarding ten free spins. Before those free spins begin, a random symbol is selected to be the special expanding symbol for the entire sequence — this selection happens once, at the start of the bonus round, and stays fixed for all ten (or more) spins within it, rather than being re-selected spin to spin. During the bonus round, whenever the chosen symbol lands anywhere on the reels as part of a winning combination, it expands to fill the entire reel it appeared on, which is what produces the format's occasional dramatic wins — a full-reel expansion of a high-value symbol can complete several winning combinations from a single land. Landing three further scatter symbols during an active bonus round retriggers the feature, awarding another ten free spins on top of the original allocation, with the same expanding symbol carrying over rather than being re-selected.

Most "Book of" titles also include a gamble (double-or-nothing) feature available after any winning spin — guessing a card's colour (red or black) doubles the win if correct, while guessing its suit specifically quadruples it, with an incorrect guess forfeiting the win entirely. This is a genuinely separate, purely even-money gamble mechanic layered on top of the core game, not connected to the expanding-symbol format itself, and available (with minor variations) across most titles in this category.

The Two Most Influential Modern Entries

Book of Dead, released by Play'n GO, is arguably the single most commercially significant "Book of" title released after the original — reported at 96.21% RTP with a 5,000x max win, and widely credited with cementing the format's popularity across the online slots market specifically, distinct from Book of Ra's original land-based success. Legacy of Dead, also Play'n GO, is closely related — sharing much of Book of Dead's underlying mechanic and visual design, reported at a slightly higher 96.58% RTP, and commonly described as a refined or alternate version of the same core game rather than an entirely separate title.

Where the Format Has Gone Since

The format has since spread across a wide range of developers well beyond its Novomatic origin — Play'n GO (Book of Dead, Legacy of Dead), Relax Gaming (Book of 99, Book of Power), NoLimit City (Book of Shadows, covered in this site's NoLimit City provider hub), Pragmatic Play (Book of Kingdoms), Quickspin (Book of Duat), and Microgaming (Book of Atem: WowPot!, Book of Mega Moolah — this second title folding the format into Microgaming's own progressive jackpot network, covered in this site's Progressive Jackpot Slots guide). This breadth is itself informative: few slot mechanics have been licensed, replicated, or independently rebuilt by quite as many separate studios as the "Book of" expanding-symbol format, a genuine testament to how well the original mechanic translated into a repeatable, studio-agnostic template.

Volatility Across the Format

Nearly every "Book of" title is built as high volatility, regardless of which studio produced it. This is a direct consequence of the expanding-symbol mechanic itself — most of a title's win potential is concentrated in the rare moments when a high-value symbol becomes the chosen expanding symbol and then lands repeatedly across the reels during free spins, rather than being spread evenly across ordinary base-game spins. This means the format rewards patience more than most: long stretches of modest or no wins between bonus rounds are the norm across the category, with the bonus round itself (and specifically, which symbol gets randomly selected to expand) doing almost all of the heavy lifting for a session's overall return. Base-game hit frequency tends to run noticeably lower than on genuinely low- or medium-volatility titles covered elsewhere on this site (Starburst, for instance), which is worth knowing before assuming a "Book of" title will play similarly to a gentler, steadier slot format.

Where to Play "Book of" Slots

Given how widely licensed and replicated this format has become, "Book of" titles are available across the large majority of UK-licensed casino operators — spanning Play'n GO, Novomatic, Relax Gaming, NoLimit City, Pragmatic Play, Quickspin, and Microgaming titles, most UK operators carrying slots from several of these studios will offer at least a handful of "Book of" titles. Specific title availability varies more by which of these studios a given operator's platform supports than by whether "Book of" slots as a category are offered at all.

A Practical Checklist Before Playing

Check which specific title you're playing before assuming shared figures — RTP ranges from 92.01% (Book of Mega Moolah, given its progressive jackpot contribution) up to 99% (Book of 99), a considerable spread across titles that share the same core mechanic.

Understand the mechanic before assuming theme alone qualifies a title — a genuine "Book of" slot uses the randomly-selected, full-reel expanding symbol specifically; similarly-themed slots without this mechanic aren't part of the same format regardless of visual similarity.

Note that Book of Atem: WowPot! and Book of Mega Moolah trade lower base RTP for jackpot potential — the same trade-off covered in detail in this site's Progressive Jackpot Slots guide applies here specifically.

Don't assume "Legacy of Dead" and "Book of Dead" are unrelated titles — they share close underlying mechanics and are commonly treated as closely related versions of the same core game by Play'n GO.

Who "Book of" Slots Genuinely Suit

Good fit: players who enjoy a well-established, repeatedly-refined mechanic across a wide choice of specific titles and RTP tiers, from Book of Mega Moolah's progressive-jackpot trade-off through to Book of 99's exceptionally high base RTP.

Less suited: players looking for genuinely novel mechanics — the "Book of" format, however well-executed across its many versions, is fundamentally the same expanding-symbol system introduced in 2005, refined rather than reinvented across nearly every subsequent release.

Frequently Asked Questions

What slot started the "Book of" format?

Novomatic's Book of Ra, released in 2005 — originally a land-based casino title before becoming a major online hit, and the direct template every subsequent "Book of" slot has built on.

What makes a slot a genuine "Book of" title, rather than just Egyptian-themed?

The mechanic specifically — a randomly-selected symbol that becomes a full-reel expanding symbol during a bonus round, usually retriggerable by landing further scatters. Theme alone doesn't qualify a title; plenty of Egyptian-themed slots don't use this mechanic at all.

Which "Book of" slot has the highest RTP?

Book of 99 (Relax Gaming), at a reported 99% RTP — considerably above every other title in the format, and among the highest RTP figures found on any slot in the wider market.

Which "Book of" slot has the biggest max win?

Book of Duat (Quickspin), reported at 32,760x stake, narrowly ahead of Book of Shadows (NoLimit City) at 30,338x.

Are Book of Dead and Legacy of Dead the same game?

Not identical, but closely related — both are Play'n GO titles sharing much of the same underlying mechanic and visual design, commonly described as alternate or refined versions of each other rather than fully separate games.

Why does Book of Atem: WowPot! have a lower RTP than other "Book of" titles?

Because it's a progressive jackpot slot — a portion of every stake is diverted into its jackpot pool rather than returned through the base game's payout structure, the same trade-off that applies to any progressive jackpot title, covered in more depth in this site's Progressive Jackpot Slots guide.

How many free spins does a typical "Book of" bonus round award?

Ten, on most titles including Book of Dead — with landing three further scatter symbols during the bonus round typically retriggering another ten on top of the original allocation.

Is the gamble feature connected to the expanding-symbol mechanic?

No — the gamble (double-or-nothing) feature, available after most winning spins on titles that offer it, is a separate, purely even-money mechanic (guess a card's colour to double a win, or its suit to quadruple it) layered on top of the core game, unrelated to how the expanding symbol itself works.

This guide is for informational purposes. RTP, volatility, and max win figures are as reported across multiple third-party sources and may vary slightly by platform configuration — always check the individual game's information screen for current, exact figures before playing. 18+ only. UKGC-licensed operators only. Gambling problem? BeGambleAware.org | National Gambling Helpline 0808 8020 133. Information correct as of October 2026.