Developer Book of 99 by Relax Gaming is a five-reel video slot with 10 paylines, high volatility and a stated 99% RTP. The game uses a Book of-style structure set in a Greek mythology theme, with a minimum bet of €0.10 and a maximum bet of €100. Players can use the demo version to play for free and practice before playing for real money.
The base game includes a special collection feature: gathering 99 book symbols triggers 10 free spins, alongside the usual three-symbol bonus trigger. In the bonus round, one of the warrior characters is selected at random before the free spins begin. During this feature, the chosen symbol gains expanding abilities and can fill the full reel.
If three or more book symbols land in the bonus round, the free spins are retriggered for another 10 rounds. This structure is designed around repeated bonus access, expanding symbols and the possibility of larger wins within the slot’s high-volatility format.
