Book of Books

Peter & Sons built Book of Books around a woodland instead of a desert — swap the pyramids for pointed evergreen trees and a trio of musicians working homemade instruments, and you have the backdrop this expanding-symbol slot plays out against. It keeps the format that made 'book of' games popular while reworking almost everything else about how the bonus unfolds.

The base grid runs five reels and three rows across ten paylines, though the layout is not fixed — landing the feature can grow it to 5x4 with twenty paylines, or 5x5 with forty. Stakes run from 10p up to £50 a spin, and a Golden Bet option raises the wager by half again in exchange for better odds of triggering the round. RTP tops out at 96.1% on its highest configuration, with high volatility and a top prize of 10,000x the stake; wins land close to a third of the time, with a measured hit frequency of 33.26%.

Low-value wins come from a run of playing-card suits — clubs, diamonds, spades and hearts — plus an axe, each paying 5x to 10x the bet for five of a kind. Above them sit a hammer, a sword and three character symbols worth 20x to 150x. A book doubles as wild and scatter: as a wild it swaps in for any regular symbol, and landing two of them in the base game hands out a power-up carried into the free spins round.

Three or more books trigger the round itself, with the grid size set by how many landed — three keeps it at 5x3, four expands it to 5x4, and five stretches it to the full 5x5. Free spins start at seven, boosted by any power-ups collected beforehand: extra spins, an additional expanding symbol, or a multiplier applied to wins from expanded symbols, with multipliers stacking as more are gathered. Rather than fixing one expanding symbol for the whole round, Book of Books redraws it on every spin, tracked on a meter beside the reels, and an expanded symbol that lands in a winning combination covers its whole reel and pays across all ten lines regardless of grid size or adjacency. Landing two or more scatters during the round retriggers it, adding spins and another power-up, and can push the grid up a size if it has not already reached its maximum.

A buy option skips straight to the round for a flat 500x the bet, taking players directly into the 5x5, forty-payline version with every power-up active from the first spin.