Build with .tumble(...), then after fading the winners call reelSet.refill({ winners, grid: nextGrid }) with the cleared cells and the new symbols. Survivors fall into the gaps and fresh symbols drop in from above.
See it work
Build with .tumble(...), then after fading the winners call reelSet.refill({ winners, grid: nextGrid }) with the cleared cells and the new symbols. Survivors fall into the gaps and fresh symbols drop in from above.