Book of Monsters isn’t a cute bedtime story, despite the cuddly monsters. It’s a wild, massive 7x7 grid slot packed with chaos, creepy charm, and monster-sized wins. Released earlier this year, this one throws out the traditional paylines in favor of cluster pays, oversized symbols, and a bonus feature that grows — literally — with every spin. If you're into games where things escalate fast and unpredictably, this is right up your alley.
Pragmatic Play went all-in on size and spectacle here, which is probably why everyone is going crazy for it. The slot delivers max win potential of 5,000x your stake, explosive clusters, and a feature that transforms a random symbol into a giant monster capable of swallowing the entire screen.
The tone might look fun and silly, but make no mistake about it — this game hits hard.
Book of Monsters uses a 7x7 grid with a cluster pays mechanic. That means you need 5+ matching symbols touching horizontally or vertically to score a win, which, to many, feels better than traditional wins. When a win lands, the matching symbols disappear, and the tumble feature drops new ones into place. This continues until no new clusters form.
Now, here’s where things get real juicy — block symbols ranging in size from 3x3 up to 7x7 can drop onto the grid at any time. These oversized symbols act as one huge symbol and can either lock in a win outright or combine with smaller symbols to form even bigger clusters. The sheer scale of the screen, combined with these chunky blocks, creates the potential for explosive payouts from a single spin. It’s fast, so be sure to hold on tight.
To unlock the main feature of this game, you simply need to land 4-7 Bonus symbols. This triggers the Free Spins round, thus giving you anywhere from 5-8 free spins depending on how many Bonus symbols triggered it. Before the round kicks off, a random symbol is chosen as the "Fat symbol." You’ll also be given the option to gamble for either more spins or a higher-paying Fat symbol.
This gamble adds a bit more risk but also opens the door for a much better bonus round. Once inside, the Fat symbol becomes the star of the show. If enough matching symbols land, it grows in size, starting from 1x1 and climbing to 3x3, 5x5, and potentially all the way to 7x7.
Every time the Fat symbol levels up, you get 1 to 3 extra free spins. So even if you start with 5 spins, you can end up with much more if the Fat symbol keeps growing. And when it finally drops in at max size, it can wipe the board and trigger enormous wins in one blow.
While the free spins feature is clearly the main draw, the base game still has enough movement to keep things interesting and fresh. Thanks to the tumble mechanic and oversized symbols, you’re looking at a hit frequency of around 1 in every 4.3 spins. That’s not bad for a game with this level of volatility.
Of course, if waiting isn’t your style, you can always buy straight into the bonus for 100x your bet. There’s also an Ante Bet option, which increases your stake just slightly and bumps the chances of landing the bonus feature naturally. Both options cater to different player types — those who like to grind and those who prefer to take a shortcut straight to the action.
Book of Monsters looks playful, but the structure is undoubtedly sharp. The 7x7 layout doesn’t feel as cluttered as you’d expect, thanks to a clear UI and colorful, cartoon-style graphics. The background is a neon-hued, eerie landscape straight out of a kid’s haunted storybook. Monsters are quirky and animated, and the soundtrack stays light but ramps up when something big is coming. It feels like an odd spinoff from the Monsters Inc. movies.
It’s a clean slot with tight pacing where the spins are quick, animations are polished, and when the Fat symbol starts expanding, you can feel the tension build with each spin. You’re not just hoping for more spins — you’re watching the symbol physically grow, take over more of the grid, and, hopefully, if you’re lucky enough, set up a monster win.
The volatility is very high, and it shows. The bonus feature doesn’t come easy unless you buy it — roughly 1 in every 291 spins. But that scarcity gives the bonus round weight. When you get in, it definitely matters. If you're chasing the big wins, you need to either hit the bonus organically, buy it, or take your chances with the gamble. Either way, the bonus round is where it’s at.
Like most high-risk slots, Book of Monsters doesn’t hand out life-changing wins freely as your odds of landing a win over 1,000x are about 1 in 101,440. Hitting the max payout of 5,000x sits at 1 in 547,945. Of course, it’s rare, but for players who love slots that play close to the edge, these are the kinds of numbers that keep the adrenaline pumping.
Even if you’re not hitting these monster wins, there are still plenty of other ways to bring in some serious GC or SC.
If you're the type of player who gets a kick out of games like Fat Rabbit, Fat Santa, or even cluster-pays titles like Reactoonz, this one will be right up your alley. It has that same escalating tension that each spin could lead to something huge if the board sets up just right.
It’s not for players who need frequent payouts or who like slow, steady wins as they grind it out. This slot is without a doubt streaky. The base game has plenty of dry stretches. But once the Fat symbol hits and starts growing, the pacing changes fast, and things get wild.
Book of Monsters proves that you don’t need a dozen features to make a great sweepstakes slot game. And without a doubt, Pragmatic Play keeps it focused — a strong base game, a bonus round that actually evolves while you play, and a high ceiling that makes every feature feel meaningful.
The oversized symbol system gives every spin a reason to pay attention. The gamble before free spins adds tension. And the Fat symbol’s growth mechanic gives the bonus real legs.
It’s bold, it’s quirky, and when it hits, eventually, it hits like a freight train made of slime and fangs.
If you’re chasing excitement, big grid energy, and that satisfying moment when a 7x7 Fat symbol lands dead center, Book of Monsters is absolutely worth your time.