One of my favorite
best free slots game that stands out for its thrilling bonus rounds and unique gameplay features is "Book of Ra" by Novomatic. This game takes players on an adventurous journey into ancient Egypt, and its standout feature is the free spins bonus. Before starting the free spins, a special expanding symbol is randomly chosen, and when it appears during the bonus round, it expands to cover the entire reel, leading to massive wins. This mechanic adds an extra layer of excitement and anticipation.