An Egyptian slot with an unusual extra reel

Book of Cats was released on July 8, 2020. Bastet, decorated cat masks and the Golden Book establish the setting, but the important design choice is the partially locked sixth reel. BGaming's rules describe a 6x3 layout: during the main game, only one cell of the last reel is open. It is therefore useful to watch that cell alongside the ordinary line combinations.

The official game profile lists ten paylines, 96.99% theoretical RTP and very high volatility. The published maximum multiplier is 8,202x the bet. At a one-unit stake, that multiplier would represent 8,202 units, although the upper limit says nothing about how likely a particular session is to approach it.

We see the attraction in the extra reel's practical role. It is visible before a bonus arrives and remains relevant when the game changes modes. Players who enjoy classic Egyptian symbols get a recognizable presentation, while the connection between the sixth cell and the bonus adds something concrete to follow.

How the sixth cell changes a result

Regular main-game combinations pay from left to right on consecutive reels. If a winning combination has formed and its matching symbol appears in the sixth cell, that symbol expands over all three positions of the last reel. The expansion complements the existing winning combination; the extra cell is not a separate guaranteed payout.

The Golden Book serves as both Wild and Scatter. In its Wild role, it helps substitute within a winning line. Three or more Books trigger ten free spins. At that point, the sixth reel opens fully, and the ordinary symbol in its previously open cell becomes the special expanding symbol. The Book itself cannot be selected for that role.

During the bonus, ordinary payouts are evaluated before the special symbol expands. Expansion requires enough occurrences of that symbol for a win. Once the requirement is met, it occupies the three positions of its reel and can pay across non-adjacent reels on the lines played. This is the main distinction from the base game, where ordinary consecutive-reel rules apply.

Free Spins, purchase and optional gamble

The bonus can be extended by landing three or more Books again. The published rules do not impose a fixed number of retriggers, so the round is not restricted to its initial ten spins. That possibility should be separated from an expectation: a particular bonus may finish without any extra award.

Buy Bonus offers direct access to the free-spin round at the price displayed on its button. The price changes with the selected stake, and purchase availability can depend on licence requirements. We would read the current total charge before confirming rather than treat an example promotional screen as a universal price list.

After a main-game win, an optional card gamble risks the current winnings. Correctly choosing the card's colour doubles that amount; correctly choosing its suit pays four times it. An incorrect choice loses the amount being gambled. Collecting instead keeps the existing result and returns to the main game, so this decision is separate from spinning the reels.

Our verdict is that Book of Cats suits players who want a familiar line slot with a visible bonus-selection mechanism. The sixth cell gives the expanding-symbol round useful context, and the fully opened last reel creates a genuine change in layout. The very high volatility label makes it a weaker fit for anyone expecting frequent, steady returns from a short visit.

Use the demo to identify the selected symbol, the locked positions and the difference between ordinary and expanded payouts. Set a spending limit before real-money play, especially before a bonus purchase or gamble. This review analyses official rules and publisher media; it does not claim a personal cash-play result.

Sources: BGaming Book of Cats game profile, official game rules and publisher Promo pack.