Free demo · independent review
Book Of Monsters
Choose a creature for the bonus, then watch matching clusters push the Fat symbol from one cell towards a full 7×7 takeover.
60-second guide
What matters before you play
Free play
Try Book Of Monsters for free
Use the demo to see whether the pace and bonus features suit you. It opens here and costs nothing.
No sign-up · no deposit · full screen available
Use the demo well
Three things to watch
- Trace clusters by shared edges
A group needs at least five matching cells connected horizontally or vertically. Giant symbols contribute many cells, but diagonal contact alone does not join groups.
- Choose Fat value against growth pace
Before Free Spins, the gamble can improve the selected symbol or the number of turns. A premium choice may pay more but still needs enough matching cells to grow.
- Count added spins at each expansion
When the Fat symbol increases in size, it also awards one to three more Free Spins. Early growth can therefore improve both board coverage and remaining time.
Our take
A genuinely visual cluster game where one monster changes the whole board
Book Of Monsters earns its theme through scale rather than decoration. The base game can drop square symbols from 3×3 up to a full 7×7, creating immediate cluster wins or crowding the board in striking ways. Free Spins choose one Fat symbol, then matching icons increase its size step by step. Every growth event also adds one to three turns, so an early expansion has compounding value. Players can gamble before the feature for more spins or a better-paying chosen icon, but neither option removes the need for matches. The game lists 96.50% RTP, high volatility and a 5,000x maximum. It is inventive and easy to watch, though starting with only five to eight spins can make a slow-growing bonus feel brutally short.
How it plays
What happens when you spin
The square grid treats symbol area as part of the payout: oversized blocks can create clusters instantly, then one selected icon becomes the bonus's growth engine.
Five connected cells create a win
Matching symbols pay as clusters when at least five cells share horizontal or vertical edges on the 7×7 board.
Giant blocks can land in the base game
Random symbols measuring 3×3, 4×4, 5×5, 6×6 or 7×7 can occupy many cells at once and count towards connected groups.
Bonus symbols set the starting turns
Four, five, six or seven Bonuses award five, six, seven or eight Free Spins before any pre-feature gamble is considered.
The Fat symbol grows through matches
A random paying symbol begins at 1×1. Enough matching cells increase its size towards 7×7 and grant one to three extra spins at each step.
Size is momentum
Early growth improves both space and time
A larger Fat symbol occupies more winning cells, while the growth event adds turns. Watch when the first expansion happens; timing often matters more than the final size alone.
Inside the game
See Book Of Monsters in action
Full, uncropped game views selected to show the reels, controls and features in context.
Is it for you?
Does Book Of Monsters match your style?
Use these points to decide whether the game's pace and features match what you enjoy.
You may like it if...
- Cluster fans wanting unusual board scale
- Players who enjoy visible feature growth
- Bonus rounds with a pre-start decision
It may not suit you if...
- The feature can begin with only five spins
- The gamble can reduce a preferred setup
- Large blocks make the board visually busy
Compare your options
What should you try next?
Choose by the way the game plays, not just by theme or maximum win.
Want a much smaller Wild-led slot?
Lucky Mouse Lucky Mouse uses ten lines and random multiplier Wild drops on a 3-4-3 grid, while Book Of Monsters fills a 7×7 board with connected blocks.
Prefer clusters with a rising trail?
Fire Stampede Ultimate Fire Stampede Ultimate advances through staged multipliers and modifiers, whereas Book Of Monsters concentrates progress inside one expanding chosen symbol.
Quick answers
Book Of Monsters FAQ
Game settings can vary between casinos. Check the information screen in the version you are playing.
How do Book Of Monsters clusters pay?
Five or more matching cells must connect through horizontal or vertical edges on the 7×7 grid.
What is the Fat symbol?
It is the selected bonus icon that grows from 1×1 towards 7×7 as enough matching symbols land, adding spins when it expands.
Can I play Book Of Monsters free?
Yes. The official demo runs here with virtual credits and no deposit.
Game facts
Book Of Monsters numbers and features
These are the game settings we could confirm. A casino may use a different version, so check the in-game information before playing for money.
Payouts & risk
- RTP
- 96.5%
- Volatility
- High
- Maximum win
- 5,000×
- Bet range
- 0.2 – £4.00
Reels & wins
- Reel layout
- 7×7
- Payout system
- Cluster Pays
Bonus features
- Features
- A selected Fat symbol grows towards 7×7
- Free spins
- Yes
- Bonus buy
- Yes
- Jackpot
- No
Release & devices
- Release date
- 19 Mar 2025
- Platforms
- Desktop, Mobile
- Theme
- Halloween
More to play
More games from Pragmatic Play
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