Ichimaga is a logic puzzle invented by Nikoli. The task is to connect all circles by horizontal and vertical lines. The number of lines connected to the circle must match the digit in that circle. Any number of lines may be connected to the empty circle (at least one). The lines must not cross other lines. The line may change direction 90 degrees no more than once.
Cross+A can solve puzzles from
Crossing Ichimaga: the lines may cross other lines; the lines cannot change direction at the point of intersection.
Magnetic Ichimaga ("Jishaku-Ichimaga"): the circles with the same digits cannot be connected.