Behind the Biggest Vault lie stacks of gold bars, overflowing safes and treasure-filled chambers waiting to be claimed. Climb through 4 Progress Levels to grow your wealth, with each stage unlocking powerful features. Cash Symbols carry multipliers up to 10x, and Free Spins trigger when 6 or more Cash or Bonus Prize symbols land, giving 3 spins that reset whenever a new symbol appears. Each Free Spins round unlocks a new level: first Cash Box, then Cash Safe, and finally Cash Vault. Cash Vault also opens Vault Spins, a special bonus where every new Cash Symbol increases an ever-growing Multiplier. Once Level 4 is reached, Bonus Prizes are added to the reels with Mini (20x), Minor (100x), Major (1000x) and the Grand (20,000x). For instant action, Feature Buy lets you dive straight into Cash Collect, Free Spins or Cash Vault.