Brand new
Our rating:
Developer: Pragmatic Play
Release date: 27th Mar 2025
Book of Monsters Slot - Screenshot
Grid Slot
RTP: 96.50%
Max Payout: 5,000x stake
Volatility: High
Min Bet: 0.20
Max Bet: 240.00
Reels: N/A
Paylines: N/A
Category: Grid slots
Themes: Space, WTF
Jackpot: No

Book of Monsters

Paul Clare
Reviewed by Paul Clare Last updated:

Books and slots have gone hand in hand for a little while now and Pragmatic Play seems to think it's time that monsters got involved as well! These creepy critters are displayed across a huge grid with the potential to land you up to 5,000x. Watch out for Fat symbols, free spins and a chance to gamble and upgrade everything along the way. Book of Monsters sounds very unpredictable but potentially spectacular.

Full review continued below ↓

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Our Rating

“Fat symbols could mean fat payouts!”

4.0 out of 5

Features
7/10
Design
8.6/10
Gameplay
7.7/10
Win potential
8.5/10

Book of Monsters Review

Watching the monsters take over and produce huge winning clusters is exciting enough in its own right. However, when you mix a little bit of slime into the equation and a free spins bonus with a chance to gamble to the top, things could get out of control!

slot feature screenshot

Gameplay & Features

This grid is pretty substantial! It stands at 7x7 and across it, you'll see royal symbols and monsters start to fall. The royal symbols pay the least with a maximum of 100x available. That sounds pretty amazing but you are going to need 49 of them to see such a payout. 

The smallest payouts come from a five-of-a-kind win and don't forget that these must be touching horizontally or vertically somewhere on the grid. The highest payers are the red monsters with 2x for the smallest group and 5,000x for a complete grid full of these slimy specimens. 

You won't see any wild or other modifiers happening during the base game, unfortunately.

It sounds like you need to make a swift exit from the base game as soon as possible and head into the free spins bonus. 

One way you can improve your chances of doing this is by paying double the original stake. For this, your spins will become seven times more likely to trigger the feature. 

Bonus Game

Landing between 4 and 7 bonus symbols is a sufficient tally to pick up 5 to 8 free spins. As soon as you start, you can look forward to a Fat symbol entering the game and this could prove to be a little special. 

Before any spins are played, you have a chance to upgrade your Fat symbol and also take a gamble on the number of spins. If you get the Fat symbol gamble right, it pushes it up to the next highest symbol in the pay table. 

You are welcome to take what you've got if you don't want to gamble it. If you reach the end of the book as you gamble your symbol, you will see your bonus game meet an untimely end. 

Fat symbols are large clusters of matching symbols that are either 2x2, 3x3, 4x4, 5x5, 6x6 or 7x7 in size. These large groups of matching symbols could pick up some big wins and you can also stretch them even larger during the bonus game. 

Your Fat symbol is designated for all of your spins but if you see another one land and it isn't overlapping the original, then you begin to build up the chance to upgrade the size of your Fat symbol. 

Players outside the UK who would like to head straight into the free spins bonus can pay 100x and negate the need to play without a Fat symbol.

Book of Monsters - Free Spins

Free Spins

By landing 3–7 scatters you can trigger up to 8 free spins and you get a Fat symbol designated from the start. You can gamble to improve the Fat Symbol and the number of spins. Separate Fat symbols land and make your original grow!

Win Potential

I took on the challenge of the base game for several hundred spins and tried my hardest to hit some large clusters. The most frequent arrivals were the royal symbols, but that was to be expected. Luckily, my spins awarded the occasional 20x plus reward but most of the time my balance struggled to get ahead. 

I entered the free spins bonus with five bonus plays and eventually levelled up my Fat symbol on the final spin. I also collected three extra spins at this point and moved on to level three within another couple of spins. Two more free spins came my way and now I was playing with a 3x3 Fat symbol. Once again I picked up more free spins and I was enjoying a 4x4 fat symbol and grabbed one more free spin to see if I could walk away with something huge. A few 15x wins turned up thanks to my designated symbol and after 14 spins, I'd collected 98.80x.

If your spins continue in a similar way and your Fat symbol is one of the top payers, you could be looking at a 5,000x max payout.

big win screenshot

Design

I really like the Book of Monsters design with loads of bright colours and cute characters to keep you amused. There's a lot of detail in every area of the game and the grid itself is buzzing with life. It's easy enough to make everything out on smaller mobile phone screens as well so everyone can get involved. The soundtrack is as weird as It gets but I think that just adds to its appeal.

Our Verdict

If Book of Monsters had a more interesting base game, this slot would have been heading for a terrific score. Unfortunately, it made everything about the bonus game and that's always a personal bugbear of mine.

I hope Pragmatic Play realises the potential in this game and goes for a sequel at some point with some exciting modifications. Nonetheless, it's a terrific-looking slot with a good amount of win potential.

Play Book of Monsters at these slot sites

Jump straight into the action and play Book of Monsters now at the following fully licenced UK slot sites. These slot sites have been thoroughly audited and reviewed by the team here at Slot Gods to ensure they offer an exceptional user experience, are trustworthy, safe, secure, and boast the best selection of online slots in their portfolio including Book of Monsters...