Draw one diagonal per square. Each number counts touching lines. No loops.
Free draw, the pencil beside Settings, is a blank board with no numbers or rules: every closed section fills with colour, loops included. Its size is chosen at the top, up to 16 × 16.
Color fills closed sections when their touching numbers match.
Tap — turn or clear a diagonal.
Drag — paint a line of diagonals.
Right-click or hold a drawn diagonal to lock or unlock it.
Blue numbers match; red numbers need attention.
More controls
Choose Slash or Backslash in Settings to paint one direction. Hint outlines a diagonal and the clues or path that force it.
Hint previews a move. Tap it again to apply.
Arrows move; Enter or Space cycles. / and \ draw; Delete clears. Shift + arrows paints. L locks or unlocks a drawn diagonal. Z undoes. Escape cancels a gesture.
For a larger board, choose Enlarge, then Pan in Settings.