| Updated: September 24, 2025When a movie becomes a box office success, it is usually followed by one or more sequels. The same can be said of online slots, where several popular series are released by different software developers. The main difference between the two industries is that, in cinema, the second or third installment of a title often rests on its laurels and rarely matches the merits of the original, whereas in online gambling, the opposite is frequently true.
An excellent example of this is the recently released Book of Secrets Extra slot. In general, creating an interesting casino game when there are already more than 26,000 predecessors in the same genre is difficult, but not for a provider of Synot Games’ caliber. Book of Secrets Extra is a 5-reel, 10-payline online slot with an RTP of up to 97.93%.
Book of Secrets Extra Theme, Graphics, and Sounds
Book of Secrets Extra is aimed at players who enjoy gambling and want to embark on an archaeological adventure in search of hidden fortunes. The slot lets players enter a pharaoh’s tomb and, with the assistance of a beautiful female explorer, lay their hands on untold riches. The playing grid actually resembles the entrance to a tomb, decorated with Egyptian symbols and a statue. The main buttons, as well as the logo, are plated in gold, alluding to the treasures hidden behind the portal. The enigmatic background audio fits the Egyptian theme perfectly and seems to hypnotize gamblers, urging them to venture deeper into the tomb to uncover ancient secrets.
Book of Secrets Extra Symbols and Payouts
Now let’s take a look at the symbols that appear on the reels and what they can bring you. The regular icons are divided into two groups: the higher tier pays for matching combinations of two to five symbols, while the lower tier requires three, four, or five identical symbols to award a win. If five icons featuring the beautiful archaeologist land on any of the 10 paylines, your bankroll will increase by 500 times your stake. The lady is quite generous, offering prizes of 1x, 10x, and 100x your bet for hitting two, three, or four symbols, respectively.
Second in power is the Pharaoh’s Head, which awards between 0.5x and 200x your bet, depending on how many icons land. The other two regular symbols in this group are a Scarab beetle and a stylized Ankh, which come with stake multipliers ranging from 0.7x to 75x.
The lower-tier symbols in the Book of Secrets Extra slot are represented by the usual card faces from 10 to A. They offer moderate payouts, the highest of which is 15 times the bet for landing five Aces or Kings. Jacks, Queens, and 10s pay 0.5x, 2.5x, or 10x the stake, respectively.
Given the slot’s title, it comes as no surprise that the Book of Secrets acts as both a Scatter and a Wild. Moreover, just like the other symbols, it awards tempting cash prizes – up to 200x the total bet.
Book of Secrets Extra Bonus Mechanics
Although the base-game payouts are not bad, they are far from life-changing, especially considering that the maximum amount you can wager is just $20. Fortunately, the Book of Secrets slot has a bonus feature that gives casino players a chance to pocket some significant sums. We are talking about Free Spins, of course, which are triggered when you hit at least three Scatter Wilds. The other option is to purchase these free spins via the Buy Feature, which will cost you 100 times the current bet.
Ten free spins are granted, but before they start, one of the regular symbols is randomly chosen as a special icon. If this special symbol lands on any reel during the bonus, the free spins are retriggered. However, the perks do not end there. If a free spin results in a winning combo, the corresponding payout is added to your balance, and then the special symbol may expand to grant an additional prize, provided enough of them are present on the grid.
If, after all this, your appetite for risk is still not satisfied, you will be happy to know that you can also take advantage of a Gamble Feature. Whenever you land a win, you can choose to gamble it in an attempt to double the amount. This is done via a card-based bonus game in which you have to guess the correct color – no surprises here. The slot machine gives you ten chances to make this prediction, and if you guess incorrectly, you lose your winnings. You can also risk only half of your winnings, thereby reducing the chance of quickly depleting your balance.
Closing Thoughts
Creating yet another game in the immensely popular “Book of” slot genre is quite a risky venture. Let’s also not forget that Synot Games’ portfolio already includes several variations – Book of Secrets, Book of Secrets 6, Book of Secrets Dice, and more. Book of Secrets Extra is still very new, and only time will tell whether this approach is well-founded. Judged on its own merits, however, Book of Secrets Extra delivers a quality gaming experience. Its financial potential should also not be underestimated, especially when the Free Spins feature is activated.