Hercules High and Mighty Slot by Light & Wonder

Hercules stares out from the reels here, a young Greek hero painted in gold and terracotta, and he is the most useful symbol you can land. He's the expanding wild, swapping in for everything except the Bonus, and any sliver of him that drops into view stretches to fill the whole reel. The action plays out on a temple terrace - sandy stone columns, a marble balustrade, a golden cloudy sky behind it - with a heroine figure, a golden lion and a stylised tree filling out the high-value Greek mythology symbols. Card-suit gems in red, purple and green handle the low end.

Land a full Hercules and the grid wakes up. The reels begin at half height, but a complete hero lifts the barrier above and the expanding reels shoot up to full height, taking you from 50 lines to 100 in one drop. That's the Mighty Reels mechanic, and it's tied entirely to getting that whole wild on screen.

Free spins come from 3, 4 or 5 Bonus scatters, paying 8, 12 or 20 spins. Worth knowing before you start them: every batch begins at half height, so you're back to chasing a full Hercules to grow the reels, wilds still expand the usual way, and retriggers are on the table.

The part I kept coming back to is Big Bet. Five linked spins at a higher stake, low symbols stripped from the reels, and Mighty Reels can stay locked at full height across the whole run. Wins pile up and pay out together at the end.