Pragmatic Play’s "Book of Vikings" slots game takes players to the rugged, mythical Viking era, encouraging them to seek fortunes in the Great Hall of Valhalla. The game is distinguished by its breathtaking visuals of cliffs and a velvet sky, creating an engaging backdrop for the play. However, the sound design could use some refinement, as certain elements create a musical discord. Players might find background Viking music from YouTube more immersive.

Boasting an impressive RTP and volatility, "Book of Vikings" delivers thrilling gameplay that balances dry spells with intense, rewarding moments. Easy to play, the game offers flexible wagering and auto-spin features, making it accessible to a wide range of users. The highlight is the Free Spins feature, activated by landing book symbols that transform into expanding wilds for big wins.

The Free Spins feature in "Book of Vikings" is the main draw, with the game dynamically shifting as expanding wilds fill entire reels, leading to exciting stacking wins. This feature alone can entice players to keep returning, eager to unlock significant rewards with each spin.

In summary, "Book of Vikings" is a commendable new addition to the 'Book of' series. While it may need some adjustments in sound design, its strong graphics, gameplay, and RTP make it a solid choice for enthusiasts of Norse-themed slots. It’s an engaging, visually appealing entry that promises entertaining gameplay and the potential for substantial wins.