Quick verdict: Book Of Demi Gods 4 is Spinomenal's Norse-mythology entry in its long-running "Book of" series, pairing a Valhalla setting with the expanding-symbol free spins format the studio has built dozens of titles around. At up to 96.14% RTP, high volatility and a 5,000x max win, it's a fairly classic book-bonus slot — the appeal is the familiar, well-tuned free spins round rather than any structural novelty.
The Story
Spinomenal released Book Of Demi Gods 4 in September 2022, the fourth mainline entry in a Book-format series it has continued to expand since (a fifth and sixth instalment have since followed). Rather than the Ancient Egyptian setting most "Book of" slots use, this instalment moves the action to Norse mythology, casting the player as a challenger to Odin, Loki, Thor and Freya inside a Valhalla-themed backdrop as they hunt for the eponymous magic book.
Theme, Gameplay & Symbols
Book Of Demi Gods 4 runs on a 5-reel, 3-row grid with 10 fixed paylines. Low-value symbols are the usual card royals (9 through Ace), while higher-value symbols carry the Norse theme — stylised depictions of Odin, Loki, Thor and Freya sit as the top-paying icons. The book symbol itself is both the game's Wild, substituting for other symbols to complete wins, and its Scatter, appearing on all five reels to trigger the free spins round.
Presentation & Sound
The presentation is consistent with Spinomenal's other Book-series titles: a stormy, gold-and-purple Asgard backdrop frames the reels, with the four Norse deity symbols rendered in a painterly, semi-realistic style rather than a cartoonish one. Symbol wins are accompanied by understated chime-based audio, with a fuller orchestral swell reserved for the free spins intro and bigger wins — standard "Book of" presentation rather than anything visually experimental.
The choice of Norse mythology over the genre's usual Ancient Egyptian setting is really the game's one point of visual differentiation. The book prop itself keeps the ornate, jewel-inlaid look that runs through the whole "Book of" family, and the four deity symbols (Odin, Loki, Thor and Freya) are drawn as serious, mature character portraits rather than stylised or exaggerated figures, keeping the tone in line with the epic-fantasy framing rather than anything that reads as aimed at a younger audience. There's no dedicated ambient loop beyond the base reel spin sound and the fuller free spins theme, which keeps the game feeling closer to a classic mechanical slot than some of Spinomenal's more elaborately scored recent releases.
How to Play Book Of Demi Gods 4
- Set your stake using the in-game bet selector. Spinomenal's own data sheet lists a 0.01–10 range per spin for this title, though UK-licensed operators cap real-money stakes at £5 per spin for players 25 and over, and £2 per spin for 18–24-year-olds, regardless of the game's own maximum.
- Press spin and watch for the book symbol landing anywhere on the five reels.
- Landing three or more book symbols on a single spin triggers the free spins round.
- At the start of free spins, one regular symbol (excluding the book) is chosen at random and becomes an expanding symbol for the round, filling entire reels wherever it lands and substantially boosting payouts.
- Additional book symbols during free spins can retrigger further free spins.
Features & Mechanics
The core feature is the free spins round and its expanding symbol mechanic: once triggered, a single regular symbol is picked to expand across full reels for the remainder of the round, which is what typically produces this game's larger wins rather than the base game's fixed-payline hits alone. Because the choice of which symbol expands is randomised at the start of the round rather than fixed, the value of any individual free spins trigger varies quite a bit — landing a high-value deity symbol as the expanding one produces a noticeably stronger round than a low-value card royal doing the same job, which is part of why the format carries a wide swing between an average trigger and a standout one.
Spinomenal's own data sheet also lists a Buy Feature for this title, letting a player pay a lump sum for direct entry to the free spins round in markets where operators choose to offer it — UK-licensed operators do not offer feature-buy options to UK players, following the UK Gambling Commission's 2020 guidance on the format, so this is not something UK players will find live at any brand we list. The game also supports Spinomenal's Free Spins Promo tools, which let an operator award free spins on this title as a standalone promotional mechanic outside the in-game bonus round; any such offer is subject to the same UK wagering-requirement and terms-visibility rules as any other bonus (see our wagering requirements guide for how that works in practice).
Volatility & Win Potential
Spinomenal publishes four selectable RTP configurations for Book Of Demi Gods 4 — 88.94%, 91.71%, 93.96% and 96.14% — with 96.14% being the top published figure and the one most UK-facing operators run. The studio rates the game high volatility, and its own data sheet lists a maximum win of 5,000x the total bet, reached through a strong run of expanding-symbol free spins rather than any jackpot mechanic. Bet range on the data sheet runs 0.01–10 per spin, though UK players are capped at £5 per spin (25+) or £2 per spin (18–24) by their operator regardless of that published maximum.
Pros & Cons
- Pro: A well-tuned, classic expanding-symbol free spins round that rewards patience.
- Pro: High published RTP ceiling (96.14%) among Spinomenal's Book-series titles.
- Pro: Straightforward, easy-to-learn rules for players new to "Book of" slots.
- Con: High volatility means the free spins trigger can take a while to land.
- Con: The format itself (book Wild/Scatter, expanding symbol) is very close to Spinomenal's other Book-series releases and much of the wider market, so it won't feel novel to genre regulars.
Final Verdict
Book Of Demi Gods 4 doesn't try to reinvent the "Book of" template — it executes it well, with a distinct Norse mythology setting, a high published RTP ceiling and a free spins round that can pay out strongly once the expanding symbol lines up. It's a solid pick for players who already enjoy the format and want a change of scenery from the genre's usual Egyptian setting.
