Two tiles may be cleared if you can draw an unbroken imaginary line between them. No jumping over other tiles! The line can change direction up to twice, for a maximum of three parts.
For a leisurely game, pick Casual mode. You can ask for a Hint or Undo a move if you get stuck. For a more exciting challenge, try the Timed mode and race against your best times.
Work your brain cells with six different layouts, each one bigger than the last. Warm up with the nano 7x4 layout, and advance to the gigantic ultra 18x6 layout that packs 108 tiles onto your screen.