Drawesome: free puzzle app for iphone, ipad

Look at the image on the left. Can you draw it without lifting your pen/pencil and without tracing a line? This was a very popular pencil puzzle for elementary school kids.

Can you draw the same shape without crossing a line? Yes it's possible. If you can, take an introductory course in Topology. If you do, all of these puzzles become quite easy.

Drawesome is not the first puzzle app of this kind. But a good friend of mine really likes this. The first 16 levels are free. After that, there are 84  more levels for a nominal charge.