Book of Books is played on a 5-reel, 3-row game grid with 10 paylines for determining winning combinations. In this game, however, the grid can expand to 5x4 with 20 paylines or 5x5 with 40 paylines. How this transpires is described in greater detail below. Book of Books can be played on any device and accepts bets ranging from 0.10to 50 per turn; when the Golden Bet is activated, the stakes increase by 50 percent, increasing the likelihood of triggering the bonus game. Mathematically highly volatile, it appears that regardless of how Book of Books is played, its maximum RTP is 96.1%, though lower variants are also available.
Minimum winning combinations consist of three low-pay symbols or two premiums. Club, diamond, spade, heart, and axe pay 5 to 10 times the wager for five of a kind, while hammers, swords, and the three character insignia pay 20 to 150 times the wager for five of a kind. The wilds have the same value as the highest-paying symbol and can substitute for any non-expanded regular paying symbol.
To clarify, Book of Books also features a wild symbol and a scatter symbol that are both shaped like books. When two scatter symbols appear in the main game, a power-up is added to the free spins round. Power-ups can be 1 or 2 additional free spins, an additional expanding symbol, or an x1 or x2 expanding multiplier that multiplies expanded symbol wins. When these expanding multipliers are collected, they are added together.
Free spins are activated when three or more scatter symbols appear in the primary game. Players are rewarded as follows: