Tumbles
Symbols pay anywhere on the grid, so watch the whole screen rather than lines. When a combination wins, it is paid and the winning symbols vanish. Everything above drops down, new symbols fall in from the top, and the grid checks again. There is no cap on how many tumbles one spin can chain, and the balance only updates once the last tumble of the sequence has played out, which is why the win counter can climb for a while before your credit moves.