Wild Stack Frenzy Slot by Yggdrasil Gaming

Yggdrasil borrowed this engine wholesale. Stacked wilds carrying multiplier numbers, Avalanche cascades clearing winners and dropping fresh symbols, a guaranteed-stack ante toggle - none of it is new to the studio or the wider market. What's actually worth paying attention to is how the multiplier ladder is structured per stack, because that's the one piece the math hangs on.

Every Wild lands as a vertical stack between 3 and 6 segments tall in base play, and each segment of that stack carries its own incremental multiplier - segment one is x1, segment two is x2, climbing up to x6 on a full six-tall column. The multiplier that matters is whichever segment falls on the winning payline. So a x6 stack contributing only its bottom cell to a 5-of-a-kind on row 3 still scores at x1, not x6. The chase is for tall stacks landing in the right vertical position, not just tall stacks generally. Wins pay both ways across the 20 lines, which doubles the number of payline geometries a single stack can light up.

Free Spins extends the ceiling. 3, 4 or 5 scatters trigger 7, 9 or 11 spins, and inside the round Wild Stacks can grow up to 10 segments tall with per-segment multipliers reaching x10. Retriggers stack on top, no cap on extra spins. Avalanche keeps cascading inside the round too, and there is the unusual Incoming Wild Stacks rule - after a winning cascade, a stack can be telegraphed above a random reel, ready to drop in on the next clear. That telegraphing is the only real visibility you get into when the engine is about to swing.

Two paths to skip the wait. The Golden ante toggle at 10x stake guarantees a Wild Stack on the reels for that single spin, useful for grinding cascades without committing to a full bonus buy. The Buy Bonus at 60x drops you straight into 7 Free Spins, the lowest tier on the trigger ladder. Note this is a single-tier buy menu, no choice between 9 or 11 spin entries.

The cabinet sits inside a fossil chamber. A 5x3 grid surrounded by jagged stone walls embedded with mammoth and sabretooth skulls, ribcages curling in from the edges, violet amethyst clusters glowing along the cave floor. High-pay icons are bone-themed (mammoth skull, sabretooth, ribcage, curved tusk), lows are stylised runic stones in purple, red, blue and green. The Wild Stacks themselves print in bright gold against the muted slate-and-amber palette, with the multiplier number stamped large on each segment so reading the column at a glance is straightforward. Raptor 2 DoubleMax is the studio's other recent prehistoric outing if the palaeolithic angle holds appeal.