Place some boats (one cell wide) in the diagram. Boats cannot touch each other and cannot touch lighthouses, not even diagonally. The internal numbers represent lighthouses that illuminate the indicate number of boats horizontally and vertically. Every boat is illuminated by at least one lighthouse. Lighthouses and boats don't obscure other boats.
MOUSE: Click on a square to place a boat. Click again to mark that there can't be a boat. A third click will eliminate any symbol.
KEYBOARD: Press 'b' to place a boat. Press '-' to mark that there can't be a boat. Press DEL to eliminate any symbol.
