Move Dots: free puzzle app game for iphone, ipad

Move Dots is a free puzzle app game. It's classic in the sense that these types of puzzles have been posed for many years.  The directions are pretty simple.

Grab 2 adjacent dots and move them to an empty space. Then grab 2 more adjacent dots and keep doing this until the arrangement matches the image at the bottom.

There are 60 levels. I've done 15.

Did I mention that Move Dots is free?