On each spin, every winning symbol, SCATTERs included, stays put on the reels, while the rest vanish. These remaining symbols slide down, while new ones swoop in to fill the gaps. If additional matching symbols join an existing or fresh winning combo, those symbols, along with SCATTERs, cling to the reels for another round. When no more symbols can create a winning combination, the cascade finishes, and winnings are tallied up.