Number Link - Link number dots comes from Kyung-Hun Kim. He contacted me 3 years ago but I didn't see the email until recently. Yes, I feel guilty. Because this is a very good game.
The object is to draw a single path connecting the numbers in the order 1, 2, 3, 1, 2, 3 etc until all are connected.  Lines cannot cross. The key piece is figuring out where the starting point must be. Or the end point.
If you liked Stroke! then you will like this game too.

At the moment I've done about 22 of the 450 Hard levels.

https://itunes.apple.com/us/app/number-link-link-number-dots/id952097094"mt=8

...