Click or touch a ball to start a chain. Drag through balls of
the same color to link them together. Drag back to the previous
ball to undo the last link. Release to finish: chains of fewer
than the minimum vanish; chains with enough balls clear all
linked balls (score: 10 × length²). If the entry gets blocked
and a new ball cannot drop in, the run ends—restart to try
again. Pause/resume with the Pause button or Escape key.