Book of Oil — Full Slot Analysis

Book of Oil by Endorphina features a 5x3 reel setup with 10 adjustable paylines, where wins form from left to right on enabled lines, supporting bets from 0.01 to 100 per spin and options like turbo mode and autoplay up to 100 spins. Gameplay centers on standard spins augmented by the Book symbol, which acts as both Wild (substituting for other symbols except the special expanding one in free spins) and Scatter, triggering 10 free spins when landing three or more anywhere on the reels. In free spins, a random special symbol is selected that expands to cover entire reels after regular payouts, paying in adjacent and non-adjacent positions on active paylines, with retrigger potential and no Wild substitution for it. Additional elements include a gamble feature for doubling wins by guessing card color or suit, and a Bonus Pop buy option to purchase the free spins round directly. Visually, the game employs a black-and-gold aesthetic evoking oil tycoon luxury, with symbols like oil derricks, barrels, tycoons, and styled card royals set against shimmering oil rivers and derricks, blending opulence with industrial motifs. It stands out through its fusion of classic 'Book of' mechanics with an unconventional oil exploration theme, medium volatility balancing frequent smaller wins from low symbols with high potential up to 5000x via expanding symbols in bonuses, alongside practical controls for customized play.