Loyal Blog Follower Joel told me about Strand. It's similar to a series of puzzle books from Japan. The concept is called Hashi.  If a circle has 6 in it, that means there are 6 bridges emanating from it. There have been numerous puzzle apps that duplicate the concept.

What's cool with Strand:
1. Bridges can bend around the black points. 2. Portals
3. Different colored circles. Blue circles must match up. However, some circles have 2 colors.

The first 2 sections have 50 free levels or so. I did them all. After that, they cost $.99 for each group of 25.
https://itunes.apple.com/de/app/strand/id709721963"mt=8

...